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1.
Proc Natl Acad Sci U S A ; 120(52): e2306700120, 2023 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-38109540

RESUMO

Monoclonal antibodies (mAbs) have successfully been developed for the treatment of a wide range of diseases. The clinical success of mAbs does not solely rely on optimal potency and safety but also require good biophysical properties to ensure a high developability potential. In particular, nonspecific interactions are a key developability parameter to monitor during discovery and development. Despite an increased focus on the detection of nonspecific interactions, their underlying physicochemical origins remain poorly understood. Here, we employ solution-based microfluidic technologies to characterize a set of clinical-stage mAbs and their interactions with commonly used nonspecificity ligands to generate nonspecificity fingerprints, providing quantitative data on the underlying physical chemistry. Furthermore, the solution-based analysis enables us to measure binding affinities directly, and we evaluate the contribution of avidity in nonspecific binding by mAbs. We find that avidity can increase the apparent affinity by two orders of magnitude. Notably, we find that a subset of these highly developed mAbs show nonspecific electrostatic interactions, even at physiological pH and ionic strength, and that they can form microscale particles with charge-complementary polymers. The group of mAb constructs flagged here for nonspecificity are among the worst performers in independent reports of surface and column-based screens. The solution measurements improve on the state-of-the-art by providing a stand-alone result for individual mAbs without the need to benchmark against cohort data. Based on our findings, we propose a quantitative solution-based nonspecificity score, which can be integrated in the development workflow for biological therapeutics and more widely in protein engineering.


Assuntos
Anticorpos Monoclonais , Engenharia de Proteínas , Humanos
2.
Proc Natl Acad Sci U S A ; 120(15): e2210332120, 2023 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-37011217

RESUMO

Nonspecific interactions are a key challenge in the successful development of therapeutic antibodies. The tendency for nonspecific binding of antibodies is often difficult to reduce by rational design, and instead, it is necessary to rely on comprehensive screening campaigns. To address this issue, we performed a systematic analysis of the impact of surface patch properties on antibody nonspecificity using a designer antibody library as a model system and single-stranded DNA as a nonspecificity ligand. Using an in-solution microfluidic approach, we find that the antibodies tested bind to single-stranded DNA with affinities as high as KD = 1 µM. We show that DNA binding is driven primarily by a hydrophobic patch in the complementarity-determining regions. By quantifying the surface patches across the library, the nonspecific binding affinity is shown to correlate with a trade-off between the hydrophobic and total charged patch areas. Moreover, we show that a change in formulation conditions at low ionic strengths leads to DNA-induced antibody phase separation as a manifestation of nonspecific binding at low micromolar antibody concentrations. We highlight that phase separation is driven by a cooperative electrostatic network assembly mechanism of antibodies with DNA, which correlates with a balance between positive and negative charged patches. Importantly, our study demonstrates that both nonspecific binding and phase separation are controlled by the size of the surface patches. Taken together, these findings highlight the importance of surface patches and their role in conferring antibody nonspecificity and its macroscopic manifestation in phase separation.


Assuntos
Anticorpos Monoclonais , DNA de Cadeia Simples , Anticorpos Monoclonais/química , Interações Hidrofóbicas e Hidrofílicas
3.
Anal Chem ; 95(12): 5362-5368, 2023 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-36930285

RESUMO

Protein-based biologics are highly suitable for drug development as they exhibit low toxicity and high specificity for their targets. However, for therapeutic applications, biologics must often be formulated to elevated concentrations, making insufficient solubility a critical bottleneck in the drug development pipeline. Here, we report an ultrahigh-throughput microfluidic platform for protein solubility screening. In comparison with previous methods, this microfluidic platform can make, incubate, and measure samples in a few minutes, uses just 20 µg of protein (>10-fold improvement), and yields 10,000 data points (1000-fold improvement). This allows quantitative comparison of formulation excipients, such as sodium chloride, polysorbate, histidine, arginine, and sucrose. Additionally, we can measure how solubility is affected by the combinatorial effect of multiple additives, find a suitable pH for the formulation, and measure the impact of mutations on solubility, thus enabling the screening of large libraries. By reducing material and time costs, this approach makes detailed multidimensional solubility optimization experiments possible, streamlining drug development and increasing our understanding of biotherapeutic solubility and the effects of excipients.


Assuntos
Excipientes , Microfluídica , Solubilidade , Polissorbatos , Proteínas
4.
Blood ; 138(14): 1258-1268, 2021 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-34077951

RESUMO

Hemophilia A is a bleeding disorder resulting from deficient factor VIII (FVIII), which normally functions as a cofactor to activated factor IX (FIXa) that facilitates activation of factor X (FX). To mimic this property in a bispecific antibody format, a screening was conducted to identify functional pairs of anti-FIXa and anti-FX antibodies, followed by optimization of functional and biophysical properties. The resulting bispecific antibody (Mim8) assembled efficiently with FIXa and FX on membranes, and supported activation with an apparent equilibrium dissociation constant of 16 nM. Binding affinity with FIXa and FX in solution was much lower, with equilibrium dissociation constant values for FIXa and FX of 2.3 and 1.5 µM, respectively. In addition, the activity of Mim8 was dependent on stimulatory activity contributed by the anti-FIXa arm, which enhanced the proteolytic activity of FIXa by 4 orders of magnitude. In hemophilia A plasma and whole blood, Mim8 normalized thrombin generation and clot formation, with potencies 13 and 18 times higher than a sequence-identical analogue of emicizumab. A similar potency difference was observed in a tail vein transection model in hemophilia A mice, whereas reduction of bleeding in a severe tail-clip model was observed only for Mim8. Furthermore, the pharmacokinetic parameters of Mim8 were investigated and a half-life of 14 days shown in cynomolgus monkeys. In conclusion, Mim8 is an activated FVIII mimetic with a potent and efficacious hemostatic effect based on preclinical data.


Assuntos
Anticorpos Biespecíficos/uso terapêutico , Hemofilia A/tratamento farmacológico , Hemorragia/tratamento farmacológico , Animais , Fator IXa/antagonistas & inibidores , Fator VIIIa/uso terapêutico , Fator X/antagonistas & inibidores , Feminino , Humanos , Masculino , Camundongos Endogâmicos C57BL
5.
Mol Pharm ; 20(2): 1323-1330, 2023 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-36668814

RESUMO

Monoclonal antibodies (mAbs) are often formulated as high-protein-concentration solutions, which in some cases can exhibit physical stability issues such as high viscosity and opalescence. To ensure that mAb-based drugs can meet their manufacturing, stability, and delivery requirements, it is advantageous to screen for and select mAbs during discovery that are not prone to such behaviors. It has been recently shown that both these macroscopic properties can be predicted to a certain extent from the diffusion interaction parameter (kD), which is a measure of self-association under dilute conditions.1 However, kD can be challenging to measure at the early stage of discovery, where a relatively large amount of a high-purity material, which is required by traditional methods, is often not available. In this study, we demonstrate asymmetric field-flow fractionation (AF4) as a tool to measure self-association and therefore identify antibodies with problematic issues at high concentrations. The principle lies on the ability to concentrate the sample close to the membrane during the injection mode, which can reach formulation-relevant concentrations (>100 mg/mL).2 By analyzing a well-characterized library of commercial antibodies, we show that the measured retention time of the antibodies allows us to pinpoint molecules that exhibit issues at high concentrations. Remarkably, our AF4 assay requires very little (30 µg) sample under dilute conditions and does not need extensive sample purification. Furthermore, we show that a polyethylene glycol (PEG) precipitation assay provides results consistent with AF4 and moreover can further differentiate molecules with issues of opalescence or high viscosity. Overall, our results delineate a two-step strategy for the identification of problematic variants at high concentrations, with AF4 for early developability screening, followed by a PEG assay to validate the problematic molecules and further discriminate between opalescence or high-viscosity issues. This two-step antibody selection strategy enables us to select antibodies early in the discovery process, which are compatible with high-concentration formulations.


Assuntos
Anticorpos Monoclonais , Polietilenoglicóis/química
6.
Mol Pharm ; 18(10): 3843-3853, 2021 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-34519511

RESUMO

In addition to activity, successful biological drugs must exhibit a series of suitable developability properties, which depend on both protein sequence and buffer composition. In the context of this high-dimensional optimization problem, advanced algorithms from the domain of machine learning are highly beneficial in complementing analytical screening and rational design. Here, we propose a Bayesian optimization algorithm to accelerate the design of biopharmaceutical formulations. We demonstrate the power of this approach by identifying the formulation that optimizes the thermal stability of three tandem single-chain Fv variants within 25 experiments, a number which is less than one-third of the experiments that would be required by a classical DoE method and several orders of magnitude smaller compared to detailed experimental analysis of full combinatorial space. We further show the advantage of this method over conventional approaches to efficiently transfer historical information as prior knowledge for the development of new biologics or when new buffer agents are available. Moreover, we highlight the benefit of our technique in engineering multiple biophysical properties by simultaneously optimizing both thermal and interface stabilities. This optimization minimizes the amount of surfactant in the formulation, which is important to decrease the risks associated with corresponding degradation processes. Overall, this method can provide high speed of converging to optimal conditions, the ability to transfer prior knowledge, and the identification of new nonlinear combinations of excipients. We envision that these features can lead to a considerable acceleration in formulation design and to parallelization of operations during drug development.


Assuntos
Produtos Biológicos/administração & dosagem , Composição de Medicamentos/métodos , Aprendizado de Máquina , Teorema de Bayes , Produtos Biológicos/uso terapêutico , Avaliação Pré-Clínica de Medicamentos/métodos , Humanos , Sistemas de Liberação de Fármacos por Nanopartículas/administração & dosagem
7.
Biochemistry ; 58(24): 2750-2759, 2019 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-31117388

RESUMO

Aggregation can be a major challenge in the development of antibody-based pharmaceuticals as it can compromise the quality of the product during bioprocessing, formulation, and drug administration. To avoid aggregation, developability assessment is often run in parallel with functional optimization in the early screening phases to flag and deselect problematic molecules. As developability assessment can be demanding with regard to time and resources, there is a high focus on the development of molecule design strategies for engineering molecules with a high developability potential. Previously, Dudgeon et al. [(2012) Proc. Natl. Acad. Sci. U. S. A. 109, 10879-10884] demonstrated how Asp substitutions at specific positions in human variable domains and single-chain variable fragments could decrease the aggregation propensity. Here, we have investigated whether these Asp substitutions would improve the developability potential of a murine antigen binding fragment (Fab). A full combinatorial library consisting of 393 Fab variants with single, double, and triple Asp substitutions was first screened in silico with Rosetta; thereafter, 26 variants with the highest predicted thermodynamic stability were selected for production. All variants were subjected to a set of developability studies. Interestingly, most variants had thermodynamic stability on par with or improved relative to that of the wild type. Twenty-five of the variants exhibited improved nonspecificity. Half of the variants exhibited improved aggregation resistance. Strikingly, while we observed remarkable improvement in the developability potential, the Asp substitutions had no substantial effect on the antigenic binding affinity. Altogether, by combining the insertion of negative charges and the in silico screen based on computational models, we were able to improve the developability of the Fab rapidly.


Assuntos
Ácido Aspártico/química , Fragmentos Fab das Imunoglobulinas/química , Substituição de Aminoácidos , Animais , Antígenos/imunologia , Simulação por Computador , Células HEK293 , Humanos , Fragmentos Fab das Imunoglobulinas/genética , Fragmentos Fab das Imunoglobulinas/imunologia , Camundongos , Biblioteca de Peptídeos , Multimerização Proteica/genética , Estabilidade Proteica
8.
Proc Natl Acad Sci U S A ; 113(32): E4708-15, 2016 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-27457957

RESUMO

Emerging evidence strongly suggests that chaperone proteins are cytoprotective in neurodegenerative proteinopathies involving protein aggregation; for example, in the accumulation of aggregated α-synuclein into the Lewy bodies present in Parkinson's disease. Of the various chaperones known to be associated with neurodegenerative disease, the small secretory chaperone known as proSAAS (named after four residues in the amino terminal region) has many attractive properties. We show here that proSAAS, widely expressed in neurons throughout the brain, is associated with aggregated synuclein deposits in the substantia nigra of patients with Parkinson's disease. Recombinant proSAAS potently inhibits the fibrillation of α-synuclein in an in vitro assay; residues 158-180, containing a largely conserved element, are critical to this bioactivity. ProSAAS also exhibits a neuroprotective function; proSAAS-encoding lentivirus blocks α-synuclein-induced cytotoxicity in primary cultures of nigral dopaminergic neurons, and recombinant proSAAS blocks α-synuclein-induced cytotoxicity in SH-SY5Y cells. Four independent proteomics studies have previously identified proSAAS as a potential cerebrospinal fluid biomarker in various neurodegenerative diseases. Coupled with prior work showing that proSAAS blocks ß-amyloid aggregation into fibrils, this study supports the idea that neuronal proSAAS plays an important role in proteostatic processes. ProSAAS thus represents a possible therapeutic target in neurodegenerative disease.


Assuntos
Neuropeptídeos/fisiologia , alfa-Sinucleína/metabolismo , Animais , Células Cultivadas , Humanos , Corpos de Lewy/metabolismo , Neuropeptídeos/química , Síndromes Neurotóxicas/prevenção & controle , Agregados Proteicos , Multimerização Proteica , Ratos , Substância Negra/metabolismo , alfa-Sinucleína/toxicidade
9.
Biochim Biophys Acta ; 1848(9): 1897-907, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25666871

RESUMO

The deposition of amyloid material has been associated with many different diseases. Although these diseases are very diverse the amyloid material share many common features such as cross-ß-sheet structure of the backbone of the proteins deposited. Another common feature of the aggregation process for a wide variety of proteins is the presence of prefibrillar oligomers. These oligomers are linked to the cytotoxicity occurring during the aggregation of proteins. These prefibrillar oligomers interact extensively with lipid membranes and in some cases leads to destabilization of lipid membranes. This interaction is however highly dependent on the nature of both the oligomer and the lipids. Anionic lipids are often required for interaction with the lipid membrane while increased exposure of hydrophobic patches from highly dynamic protein oligomers are structural determinants of cytotoxicity of the oligomers. To explore the oligomer lipid interaction in detail the interaction between oligomers of α-synuclein and the 4th fasciclin-1 domain of TGFBIp with lipid membranes will be examined here. For both proteins the dynamic species are the ones causing membrane destabilization and the membrane interaction is primarily seen when the lipid membranes contain anionic lipids. Hence the dynamic nature of oligomers with exposed hydrophobic patches alongside the presence of anionic lipids could be essential for the cytotoxicity observed for prefibrillar oligomers in general. This article is part of a Special Issue entitled: Lipid-protein interactions.


Assuntos
Lipídeos de Membrana/química , Proteínas de Membrana/química , Dobramento de Proteína , Multimerização Proteica , Animais , Membrana Celular/química , Membrana Celular/metabolismo , Humanos , Lipídeos de Membrana/metabolismo , Proteínas de Membrana/metabolismo , Modelos Moleculares , Doenças Neurodegenerativas/metabolismo , Ligação Proteica
10.
J Biol Chem ; 289(31): 21299-310, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-24907278

RESUMO

Oligomeric species of various proteins are linked to the pathogenesis of different neurodegenerative disorders. Consequently, there is intense focus on the discovery of novel inhibitors, e.g. small molecules and antibodies, to inhibit the formation and block the toxicity of oligomers. In Parkinson disease, the protein α-synuclein (αSN) forms cytotoxic oligomers. The flavonoid epigallocatechin gallate (EGCG) has previously been shown to redirect the aggregation of αSN monomers and remodel αSN amyloid fibrils into disordered oligomers. Here, we dissect EGCG's mechanism of action. EGCG inhibits the ability of preformed oligomers to permeabilize vesicles and induce cytotoxicity in a rat brain cell line. However, EGCG does not affect oligomer size distribution or secondary structure. Rather, EGCG immobilizes the C-terminal region and moderately reduces the degree of binding of oligomers to membranes. We interpret our data to mean that the oligomer acts by destabilizing the membrane rather than by direct pore formation. This suggests that reduction (but not complete abolition) of the membrane affinity of the oligomer is sufficient to prevent cytotoxicity.


Assuntos
Biopolímeros/antagonistas & inibidores , Catequina/análogos & derivados , alfa-Sinucleína/antagonistas & inibidores , Biopolímeros/metabolismo , Biopolímeros/toxicidade , Varredura Diferencial de Calorimetria , Catequina/farmacologia , Permeabilidade da Membrana Celular , Dicroísmo Circular , Técnicas In Vitro , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Ressonância Magnética Nuclear Biomolecular , Estrutura Secundária de Proteína , alfa-Sinucleína/metabolismo , alfa-Sinucleína/toxicidade
11.
Biochemistry ; 53(39): 6252-63, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25216651

RESUMO

Many neurodegenerative diseases are linked with formation of amyloid aggregates. It is increasingly accepted that not the fibrils but rather oligomeric species are responsible for degeneration of neuronal cells. Strong evidence suggests that in Parkinson's disease (PD), cytotoxic α-synuclein (αSN) oligomers are key to pathogenicity. Nevertheless, insight into the oligomers' molecular properties remains scarce. Here we show that αSN oligomers, despite a large amount of disordered structure, are remarkably stable against extreme pH, temperature, and even molar amounts of chemical denaturants, though they undergo cooperative unfolding at higher denaturant concentrations. Mutants found in familial PD lead to slightly larger oligomers whose stabilities are very similar to that of wild-type αSN. Isolated oligomers do not revert to monomers but predominantly form larger aggregates consisting of stacked oligomers, suggesting that they are off-pathway relative to the process of fibril formation. We also demonstrate that 4-(dicyanovinyl)julolidine (DCVJ) can be used as a specific probe for detection of αSN oligomers. The high stability of the αSN oligomer indicates that therapeutic strategies should aim to prevent the formation of or passivate rather than dissociate this cytotoxic species.


Assuntos
Multimerização Proteica , Desdobramento de Proteína , alfa-Sinucleína/química , Amiloide/química , Eletroforese em Gel de Poliacrilamida , Humanos , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão , Modelos Moleculares , Mutação , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Estabilidade Proteica , Espalhamento a Baixo Ângulo , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Difração de Raios X , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo
12.
J Biol Chem ; 288(2): 1114-24, 2013 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-23172224

RESUMO

Neurodegenerative diseases such as Alzheimer (AD) and Parkinson (PD) are characterized by abnormal aggregation of misfolded ß-sheet-rich proteins, including amyloid-ß (Aß)-derived peptides and tau in AD and α-synuclein in PD. Correct folding and assembly of these proteins are controlled by ubiquitously expressed molecular chaperones; however, our understanding of neuron-specific chaperones and their involvement in the pathogenesis of neurodegenerative diseases is limited. We here describe novel chaperone-like functions for the secretory protein 7B2, which is widely expressed in neuronal and endocrine tissues. In in vitro experiments, 7B2 efficiently prevented fibrillation and formation of Aß(1-42), Aß(1-40), and α-synuclein aggregates at a molar ratio of 1:10. In cell culture experiments, inclusion of recombinant 7B2, either in the medium of Neuro-2A cells or intracellularly via adenoviral 7B2 overexpression, blocked the neurocytotoxic effect of Aß(1-42) and significantly increased cell viability. Conversely, knockdown of 7B2 by RNAi increased Aß(1-42)-induced cytotoxicity. In the brains of APP/PSEN1 mice, a model of AD amyloidosis, immunoreactive 7B2 co-localized with aggregation-prone proteins and their respective aggregates. Furthermore, in the hippocampus and substantia nigra of human AD- and PD-affected brains, 7B2 was highly co-localized with Aß plaques and α-synuclein deposits, strongly suggesting physiological association. Our data provide insight into novel functions of 7B2 and establish this neural protein as an anti-aggregation chaperone associated with neurodegenerative disease.


Assuntos
Peptídeos beta-Amiloides/antagonistas & inibidores , Doenças Neurodegenerativas/metabolismo , Proteína Secretora Neuroendócrina 7B2/fisiologia , alfa-Sinucleína/antagonistas & inibidores , Idoso , Sequência de Aminoácidos , Peptídeos beta-Amiloides/metabolismo , Animais , Morte Celular/fisiologia , Feminino , Hipocampo/metabolismo , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Transgênicos , Microscopia Eletrônica de Transmissão , Dados de Sequência Molecular , Proteína Secretora Neuroendócrina 7B2/química , Proteína Secretora Neuroendócrina 7B2/metabolismo , Substância Negra/metabolismo , alfa-Sinucleína/metabolismo
13.
Biochim Biophys Acta ; 1834(3): 677-87, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23313095

RESUMO

Ribosomal protein S6 fibrillates readily at slightly elevated temperatures and acidic pH. We find that S6 fibrillation is retarded rather than favored when the protein concentration is increased above a threshold concentration of around 3.5mg/mL. We name this threshold concentration C(FR), the concentration at which fibrillation is retarded. Our data are consistent with a model in which this inhibition is due to the formation of an off-pathway oligomeric species with native-like secondary structure. The oligomeric species dominates at high protein concentrations but exists in dynamic equilibrium with the monomer so that seeding with fibrils can overrule oligomer formation and favors fibrillation under C(FR) conditions. Thus, fibrillation competes with formation of off-pathway oligomers, probably due to a monomeric conversion step that is required to commit the protein to the fibrillation pathway. The S6 oligomer is resistant to pepsin digestion. We also report that S6 forms different types of fibrils dependent on protein concentration. Our observations highlight the multitude of conformational states available to proteins under destabilizing conditions.


Assuntos
Conformação Proteica , Multimerização Proteica , Proteínas Quinases S6 Ribossômicas/química , Proteínas Quinases S6 Ribossômicas/metabolismo , Dicroísmo Circular , Eletroforese em Gel de Poliacrilamida , Concentração de Íons de Hidrogênio , Cinética , Microscopia de Força Atômica , Modelos Químicos , Modelos Moleculares , Mutação , Proteólise , Proteínas Quinases S6 Ribossômicas/genética , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Fatores de Tempo
14.
J Am Chem Soc ; 136(10): 3859-68, 2014 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-24527756

RESUMO

Studies of proteins' formation of amyloid fibrils have revealed that potentially cytotoxic oligomers frequently accumulate during fibril formation. An important question in the context of mechanistic studies of this process is whether or not oligomers are intermediates in the process of amyloid fibril formation, either as precursors of fibrils or as species involved in the fibril elongation process or instead if they are associated with an aggregation process that is distinct from that generating mature fibrils. Here we describe and characterize in detail two well-defined oligomeric species formed by the protein α-synuclein (αSN), whose aggregation is strongly implicated in the development of Parkinson's disease (PD). The two types of oligomers are both formed under conditions where amyloid fibril formation is observed but differ in molecular weight by an order of magnitude. Both possess a degree of ß-sheet structure that is intermediate between that of the disordered monomer and the fully structured amyloid fibrils, and both have the capacity to permeabilize vesicles in vitro. The smaller oligomers, estimated to contain ∼30 monomers, are more numerous under the conditions used here than the larger ones, and small-angle X-ray scattering data suggest that they are ellipsoidal with a high degree of flexibility at the interface with solvent. This oligomer population is unable to elongate fibrils and indeed results in an inhibition of the kinetics of amyloid formation in a concentration-dependent manner.


Assuntos
Amiloide/química , alfa-Sinucleína/química , Amiloide/metabolismo , Amiloide/ultraestrutura , Humanos , Cinética , Doença de Parkinson/metabolismo , Agregados Proteicos , Conformação Proteica , Multimerização Proteica , Espalhamento a Baixo Ângulo , Difração de Raios X , alfa-Sinucleína/metabolismo , alfa-Sinucleína/ultraestrutura
15.
Analyst ; 139(4): 749-56, 2014 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-24343298

RESUMO

Amyloid formation of proteins and peptides is an important biomedical and biotechnological problem, intensively studied and yet not fully understood. In this context, the development of fast and reliable methods for real-time monitoring of protein misfolding is of particular importance for unambiguous establishment of disease-, drug- and environmentally induced mechanisms of protein aggregation. Here we show that the extent of aggregation of α-synuclein (αSN), involved in Parkinson's disease and other neurodegenerative disorders, can be electrochemically monitored by oxidizing tyrosine (Tyr) residues surface-exposed in monomeric αSN and buried in fibrillated αSN adsorbed onto graphite electrodes. Adsorption of αSN, analyzed through the Tyr electrochemistry, followed the Langmuir adsorption isotherm. The degree of electrooxidation of Tyr in αSN decreased upon protein fibrillation and correlated with the extent of αSN aggregation determined by the spectroscopic analysis of the fibrillation process. Minor changes in the adsorption state of αSN were followed through the shift of the Tyr oxidation potential, consistent with the compact and less-compact/unfolded conformation of αSN. Our results allow reliable electroanalysis of the extent of αSN fibrillation in vitro and offer an efficient tool for future in vivo monitoring of the protein conformational state.


Assuntos
Amiloide/análise , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , alfa-Sinucleína/análise , Amiloide/biossíntese , Amiloide/metabolismo , Eletrodos , Grafite/química , Humanos , Oxirredução , Doença de Parkinson/diagnóstico , Dobramento de Proteína , Deficiências na Proteostase/diagnóstico , Tirosina/química
16.
Med Sci Sports Exerc ; 56(9): 1655-1663, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-38600642

RESUMO

INTRODUCTION: Maximal acceleration and deceleration tasks are frequently required in team sports, often occurring rapidly in response to external stimuli. Accelerating and decelerating can be associated with lower limb injuries; thus, knowledge of joint mechanics during these tasks can improve the understanding of both human high performance and injury mechanisms. The current study investigated the fundamental differences in lower limb joint mechanics when accelerating and decelerating by directly comparing the hip, knee, and ankle joint moments and work done between the two tasks. METHODS: Twenty participants performed maximal effort acceleration and deceleration trials, with three-dimensional marker trajectories and ground reaction forces collected simultaneously. Experimental data were combined with inverse dynamics analysis to compute joint moments and work. RESULTS: Net joint work for all lower limb joints was positive during acceleration and negative during deceleration. This occurred because of significantly greater positive work production from the ankle and hip during acceleration and significantly greater negative work production from all joints during deceleration. The largest contributions to positive work during acceleration came from the ankle, followed by the hip and knee joints, whereas the largest contributions to negative work during deceleration came from the knee and hip joints, followed by the ankle. Peak joint moments were significantly greater when decelerating compared with accelerating, except for the peak ankle plantarflexion and hip flexion moments, which were significantly greater when accelerating. CONCLUSIONS: Our findings may help to guide training interventions, which aim to enhance the performance of acceleration and deceleration tasks, while also mitigating the associated injury risk.


Assuntos
Aceleração , Articulação do Tornozelo , Desaceleração , Articulação do Quadril , Articulação do Joelho , Corrida , Humanos , Corrida/fisiologia , Articulação do Quadril/fisiologia , Fenômenos Biomecânicos , Articulação do Tornozelo/fisiologia , Masculino , Articulação do Joelho/fisiologia , Adulto Jovem , Feminino , Adulto , Extremidade Inferior/fisiologia
17.
MAbs ; 16(1): 2403156, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39364796

RESUMO

Engineered antibody formats, such as antibody fragments and bispecifics, have the potential to offer improved therapeutic efficacy compared to traditional full-length monoclonal antibodies (mAbs). However, the translation of these non-natural molecules into successful therapeutics can be hampered by developability challenges. Here, we systematically analyzed 64 different antibody constructs targeting Tumor Necrosis Factor (TNF) which cover 8 distinct molecular format families, encompassing full-length antibodies, various types of single chain variable fragments, and bispecifics. We measured 15 biophysical properties related to activity, manufacturing, and stability, scoring variants with a flag-based risk approach and a recent in silico developability profiler. Our comparative assessment revealed that overall developability is higher for the natural full-length antibody format. Bispecific antibodies, antibodies with scFv fragments at the C-terminus of the light chain, and single-chain Fv antibody fragments (scFvs) have intermediate developability properties, while more complicated formats, such as scFv- scFv, bispecific mAbs with one Fab exchanged with a scFv, and diabody formats are collectively more challenging. In particular, our study highlights the propensity for fragmentation and aggregation, both in bulk and at interfaces, for many current engineered formats.


Assuntos
Anticorpos Biespecíficos , Engenharia de Proteínas , Estabilidade Proteica , Anticorpos de Cadeia Única , Anticorpos Biespecíficos/imunologia , Anticorpos Biespecíficos/genética , Anticorpos Biespecíficos/química , Humanos , Engenharia de Proteínas/métodos , Anticorpos de Cadeia Única/imunologia , Anticorpos de Cadeia Única/genética , Anticorpos de Cadeia Única/química , Fator de Necrose Tumoral alfa/imunologia , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/química , Anticorpos Monoclonais/genética
18.
Diabetes Res Clin Pract ; : 111893, 2024 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-39414086

RESUMO

AIMS: To test the efficacy of time-restricted eating (TRE) in comparison to dietitian-led individualised dietary guidance to improve HbA1c in people with Type 2 diabetes mellitus. METHODS: In a parallel groups design, 51 adults (35-65 y) with Type 2 diabetes mellitus and overweight/obesity (HbA1c ≥6.5 % (48 mmol/mol), BMI ≥25-≤40 kg/m2) commenced a six-month intervention. Following baseline, participants were randomised to TRE (1000-1900 h) or DIET (individualised dietetic guidance) with four consultations over four months. Changes in HbA1c (primary), body composition, and self-reported adherence (secondary) were analysed using linear mixed models. A non-inferiority margin of 0.3 % (4 mmol/mol) HbA1c was set a priori. RESULTS: Forty-three participants (56 ±â€¯8 y, BMI: 33 ±â€¯5 kg/m2, HbA1c: 7.6 ±â€¯0.8 %) completed the intervention. HbA1c was reduced (P = 0.002; TRE: -0.4 % (-5 mmol/mol), DIET: -0.3 % (-4 mmol/mol)) with no group or interaction effects; TRE was non-inferior to DIET (-0.11 %, 95 %CI: -0.50 % to 0.28 %). Body mass reduced in both groups (TRE: -1.7 kg; DIET: -1.2 kg) via ∼900 kJ/d spontaneous energy reduction (P < 0.001). Self-reported adherence was higher in TRE versus DIET (P < 0.001). CONCLUSIONS: When individualised dietary guidance is not available, effective, and/or suitable, TRE may be an alternative dietary strategy to improve glycaemic control in people with Type 2 diabetes mellitus.

19.
Nat Commun ; 14(1): 1937, 2023 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-37024501

RESUMO

Biologics, such as antibodies and enzymes, are crucial in research, biotechnology, diagnostics, and therapeutics. Often, biologics with suitable functionality are discovered, but their development is impeded by developability issues. Stability and solubility are key biophysical traits underpinning developability potential, as they determine aggregation, correlate with production yield and poly-specificity, and are essential to access parenteral and oral delivery. While advances for the optimisation of individual traits have been made, the co-optimization of multiple traits remains highly problematic and time-consuming, as mutations that improve one property often negatively impact others. In this work, we introduce a fully automated computational strategy for the simultaneous optimisation of conformational stability and solubility, which we experimentally validate on six antibodies, including two approved therapeutics. Our results on 42 designs demonstrate that the computational procedure is highly effective at improving developability potential, while not affecting antigen-binding. We make the method available as a webserver at www-cohsoftware.ch.cam.ac.uk.


Assuntos
Anticorpos , Proteínas , Solubilidade , Conformação Molecular
20.
Diabetes Res Clin Pract ; 197: 110569, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36738837

RESUMO

AIMS: Examine the effect of 5 d/wk, 9-h time-restricted eating (TRE) protocol on 24-h glycaemic control in adults with type 2 diabetes (T2D). METHODS: Nineteen adults with T2D (10 F/9 M; 50 ± 9 y, HbA1c 7.6% (60 mmol/mol), BMI ∼34 kg/m2) completed a pre-post non-randomised trial comprising of a 2-wk Habitual monitoring period followed by 9-h (10:00-19:00 h) TRE for 4-wk. Glycaemic control was assessed via continuous glucose monitoring (CGM; for mean 24-h glucose concentrations, 24-h total area under the curve (AUC) and glucose variability metrics), with dietary records and physical activity monitoring. Changes in CGM measures, dietary intake and physical activity were assessed with linear mixed-effects models. RESULTS: TRE did not alter dietary energy intake, macronutrient composition or physical activity, but reduced the daily eating window (-2 h 35 min, P < 0.001). Compared to the Habitual period, 24-h glucose concentrations (mean, SD) and AUC decreased in the 4-wk TRE period (mean: -0.7 ± 1.2 mmol/L, P = 0.02; SD: -0.2 ± 0.3 mmol/L, P = 0.01; 24-h AUC: -0.9 ± 1.4 mmol/L⋅h-1 P = 0.01). During TRE, participants spent 10% more time in range (3.9-10.0 mmol/L; P = 0.02) and 10% less time above range (>10.0 mmol/L; P = 0.02). CONCLUSIONS: Adhering 5 d/wk. to 9-h TRE improved glycaemic control in adults with T2D, independent of changes in physical activity or dietary intake. CLINICAL TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry, ACTRN12618000938202.


Assuntos
Diabetes Mellitus Tipo 2 , Adulto , Humanos , Glicemia , Automonitorização da Glicemia , Controle Glicêmico , Glucose
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