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1.
Anal Chem ; 91(13): 8443-8452, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31247719

RESUMO

We report a novel immunocapture (IC)-LC-MS/MS methodology to directly measure real time in vivo receptor occupancy (RO) for a covalent binding drug in blood lysate. A small molecule quencher was added immediately after sample collection to convert the free receptor to a quencher-bound receptor (QB-R) which was measured with the drug-bound receptor (DB-R) simultaneously by LC-MS/MS after immunocapture enrichment, followed by trypsin digestion. Addition of the quencher is necessary to prevent the free receptor from ex vivo binding with the drug. The real time RO was calculated based on the concentrations of DB-R and the free receptor (which is now QB-R) that were obtained from each sample. This strategy has been successfully applied to the measurement of the RO for Bruton's tyrosine kinase (BTK) in the blood lysate of monkeys after dosing with branebrutinib (BMS-986195), a covalent BTK inhibitor being evaluated to treat rheumatoid arthritis. A custom-made quencher, which is more reactive to BTK than branebrutinib, was added in excess amount to bind with all available free BTK to form quencher-bound BTK (QB-BTK) during blood sample collection. To measure a wide range of % BTK RO, including those of <5% or >95%, the required LLOQ at 0.125 nM for QB-BTK and 0.250 nM for drug-bound BTK (DB-BTK) in blood lysate were successfully achieved by using this IC-LC-MS/MS strategy. This proof-of-concept assay demonstrated its suitability with high throughput for real time in vivo BTK RO measurement as a pharmacodynamic (PD) biomarker for clinical drug development.

2.
PLoS One ; 14(3): e0212670, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30913212

RESUMO

Immunotherapy has fundamentally changed the landscape of cancer treatment. Despite the encouraging results with the checkpoint modulators, response rates vary widely across tumor types, with a majority of patients exhibiting either primary resistance without a significant initial response to treatment or acquired resistance with subsequent disease progression. Hematopoietic progenitor kinase 1 (HPK1) is predominantly expressed in hematopoietic cell linages and serves as a negative regulator in T cells and dendritic cells (DC). While HPK1 gene knockout (KO) studies suggest its role in anti-tumor immune responses, the involvement of kinase activity and thereof its therapeutic potential remain unknown. To investigate the potential of pharmacological intervention using inhibitors of HPK1, we generated HPK1 kinase dead (KD) mice which carry a single loss-of-function point mutation in the kinase domain and interrogated the role of kinase activity in immune cells in the context of suppressive factors or the tumor microenvironment (TME). Our data provide novel findings that HKP1 kinase activity is critical in conferring suppressive functions of HPK1 in a wide range of immune cells including CD4+, CD8+, DC, NK to Tregs, and inactivation of kinase domain was sufficient to elicit robust anti-tumor immune responses. These data support the concept that an HPK1 small molecule kinase inhibitor could serve as a novel agent to provide additional benefit in combination with existing immunotherapies, particularly to overcome resistance to current treatment regimens.


Assuntos
Imunidade Celular , Vigilância Imunológica , Linfócitos/imunologia , Neoplasias Experimentais/imunologia , Proteínas Serina-Treonina Quinases/imunologia , Microambiente Tumoral/imunologia , Animais , Linhagem Celular Tumoral , Linfócitos/patologia , Camundongos , Camundongos Mutantes , Neoplasias Experimentais/genética , Mutação Puntual , Proteínas Serina-Treonina Quinases/genética , Microambiente Tumoral/genética
3.
J Med Chem ; 62(5): 2265-2285, 2019 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-30785748

RESUMO

Recently, our research group reported the identification of BMS-986104 (2) as a differentiated S1P1 receptor modulator. In comparison to fingolimod (1), a full agonist of S1P1 currently marketed for the treatment of relapse remitting multiple sclerosis (RRMS), 2 offers several potential advantages having demonstrated improved safety multiples in preclinical evaluations against undesired pulmonary and cardiovascular effects. In clinical trials, 2 was found to exhibit a pharmacokinetic half-life ( T1/2) longer than that of 1, as well as a reduced formation of the phosphate metabolite that is required for activity against S1P1. Herein, we describe our efforts to discover highly potent, partial agonists of S1P1 with a shorter T1/2 and increased in vivo phosphate metabolite formation. These efforts culminated in the discovery of BMS-986166 (14a), which was advanced to human clinical evaluation. The pharmacokinetic/pharmacodynamic (PK/PD) relationship as well as pulmonary and cardiovascular safety assessments are discussed. Furthermore, efficacy of 14a in multiple preclinical models of autoimmune diseases are presented.

4.
J Med Chem ; 59(24): 11138-11147, 2016 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-28002964

RESUMO

We describe a highly efficient route for the synthesis of 4a (BMS-986104). A key step in the synthesis is the asymmetric hydroboration of trisubstituted alkene 6. Particularly given the known difficulties involved in this type of transformation (6 → 7), the current methodology provides an efficient approach to prepare this class of compounds. In addition, we disclose the efficacy of 4a in a mouse EAE model, which is comparable to 4c (FTY720). Mechanistically, 4a exhibited excellent remyelinating effects on lysophosphatidylcholine (LPC) induced demyelination in a three-dimensional brain cell culture assay.


Assuntos
Encefalomielite Autoimune Experimental/tratamento farmacológico , Naftalenos/farmacologia , Receptores de Lisoesfingolipídeo/agonistas , Animais , Células Cultivadas , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Células HEK293 , Humanos , Linfócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Estrutura Molecular , Naftalenos/síntese química , Naftalenos/química , Relação Estrutura-Atividade
5.
J Med Chem ; 59(21): 9837-9854, 2016 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-27726358

RESUMO

Fingolimod (1) is the first approved oral therapy for the treatment of relapsing remitting multiple sclerosis. While the phosphorylated metabolite of fingolimod was found to be a nonselective S1P receptor agonist, agonism specifically of S1P1 is responsible for the peripheral blood lymphopenia believed to be key to its efficacy. Identification of modulators that maintain activity on S1P1 while sparing activity on other S1P receptors could offer equivalent efficacy with reduced liabilities. We disclose in this paper a ligand-based drug design approach that led to the discovery of a series of potent tricyclic agonists of S1P1 with selectivity over S1P3 and were efficacious in a pharmacodynamic model of suppression of circulating lymphocytes. Compound 10 had the desired pharmacokinetic (PK) and pharmacodynamic (PD) profile and demonstrated maximal efficacy when administered orally in a rat adjuvant arthritis model.


Assuntos
Desenho de Drogas , Cloridrato de Fingolimode/farmacologia , Compostos Heterocíclicos com 3 Anéis/farmacologia , Receptores de Lisoesfingolipídeo/agonistas , Animais , Artrite Experimental/tratamento farmacológico , Artrite Experimental/imunologia , Cães , Relação Dose-Resposta a Droga , Cloridrato de Fingolimode/administração & dosagem , Cloridrato de Fingolimode/química , Adjuvante de Freund/administração & dosagem , Compostos Heterocíclicos com 3 Anéis/administração & dosagem , Compostos Heterocíclicos com 3 Anéis/química , Ligantes , Linfócitos/efeitos dos fármacos , Macaca fascicularis , Masculino , Camundongos , Estrutura Molecular , Mycobacterium/efeitos dos fármacos , Ratos , Ratos Endogâmicos Lew , Relação Estrutura-Atividade , Distribuição Tecidual
6.
J Med Chem ; 59(13): 6248-64, 2016 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-27309907

RESUMO

Sphingosine-1-phosphate (S1P) is a bioactive sphingolipid metabolite that regulates a multitude of physiological processes such as lymphocyte trafficking, cardiac function, vascular development, and inflammation. Because of the ability of S1P1 receptor agonists to suppress lymphocyte egress, they have great potential as therapeutic agents in a variety of autoimmune diseases. In this article, the discovery of selective, direct acting S1P1 agonists utilizing an ethanolamine scaffold containing a terminal carboxylic acid is described. Potent S1P1 agonists such as compounds 18a and 19a which have greater than 1000-fold selectivity over S1P3 are described. These compounds efficiently reduce blood lymphocyte counts in rats through 24 h after single doses of 1 and 0.3 mpk, respectively. Pharmacodynamic properties of both compounds are discussed. Compound 19a was further studied in two preclinical models of disease, exhibiting good efficacy in both the rat adjuvant arthritis model (AA) and the mouse experimental autoimmune encephalomyelitis model (EAE).


Assuntos
Etanolamina/química , Etanolamina/farmacologia , Linfócitos/efeitos dos fármacos , Receptores de Lisoesfingolipídeo/agonistas , Animais , Artrite/tratamento farmacológico , Cães , Encefalomielite Autoimune Experimental/tratamento farmacológico , Etanolamina/farmacocinética , Etanolamina/uso terapêutico , Feminino , Haplorrinos , Humanos , Contagem de Linfócitos , Linfócitos/citologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Ratos Endogâmicos Lew , Receptores de Lisoesfingolipídeo/metabolismo , Relação Estrutura-Atividade
7.
PLoS One ; 11(6): e0157111, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27310468

RESUMO

A Chinese hamster ovary (CHO) bioprocess, where the product is a sialylated Fc-fusion protein, was operated at pilot and manufacturing scale and significant variation of sialylation level was observed. In order to more tightly control glycosylation profiles, we sought to identify the cause of variability. Untargeted metabolomics and transcriptomics methods were applied to select samples from the large scale runs. Lower sialylation was correlated with elevated mannose levels, a shift in glucose metabolism, and increased oxidative stress response. Using a 5-L scale model operated with a reduced dissolved oxygen set point, we were able to reproduce the phenotypic profiles observed at manufacturing scale including lower sialylation, higher lactate and lower ammonia levels. Targeted transcriptomics and metabolomics confirmed that reduced oxygen levels resulted in increased mannose levels, a shift towards glycolysis, and increased oxidative stress response similar to the manufacturing scale. Finally, we propose a biological mechanism linking large scale operation and sialylation variation. Oxidative stress results from gas transfer limitations at large scale and the presence of oxygen dead-zones inducing upregulation of glycolysis and mannose biosynthesis, and downregulation of hexosamine biosynthesis and acetyl-CoA formation. The lower flux through the hexosamine pathway and reduced intracellular pools of acetyl-CoA led to reduced formation of N-acetylglucosamine and N-acetylneuraminic acid, both key building blocks of N-glycan structures. This study reports for the first time a link between oxidative stress and mammalian protein sialyation. In this study, process, analytical, metabolomic, and transcriptomic data at manufacturing, pilot, and laboratory scales were taken together to develop a systems level understanding of the process and identify oxygen limitation as the root cause of glycosylation variability.


Assuntos
Metabolômica , Estresse Oxidativo/genética , Ácidos Siálicos/metabolismo , Transcriptoma/genética , Acetilcoenzima A/genética , Acetilcoenzima A/metabolismo , Animais , Células CHO , Cricetinae , Cricetulus , Perfilação da Expressão Gênica , Glucose/metabolismo , Glicólise/genética , Glicosilação , Manose/genética , Manose/metabolismo , Ácido N-Acetilneuramínico/metabolismo , Oxigênio/metabolismo
8.
ACS Med Chem Lett ; 7(3): 283-8, 2016 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-26985316

RESUMO

Clinical validation of S1P receptor modulation therapy was achieved with the approval of fingolimod (Gilenya, 1) as the first oral therapy for relapsing remitting multiple sclerosis. However, 1 causes a dose-dependent reduction in the heart rate (bradycardia), which occurs within hours after first dose. We disclose the identification of clinical compound BMS-986104 (3d), a novel S1P1 receptor modulator, which demonstrates ligand-biased signaling and differentiates from 1 in terms of cardiovascular and pulmonary safety based on preclinical pharmacology while showing equivalent efficacy in a T-cell transfer colitis model.

9.
J Med Chem ; 59(6): 2820-40, 2016 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-26924461

RESUMO

Sphingosine 1-phosphate (S1P) is the endogenous ligand for the sphingosine 1-phosphate receptors (S1P1-5) and evokes a variety of cellular responses through their stimulation. The interaction of S1P with the S1P receptors plays a fundamental physiological role in a number of processes including vascular development and stabilization, lymphocyte migration, and proliferation. Agonism of S1P1, in particular, has been shown to play a significant role in lymphocyte trafficking from the thymus and secondary lymphoid organs, resulting in immunosuppression. This article will detail the discovery and SAR of a potent and selective series of isoxazole based full agonists of S1P1. Isoxazole 6d demonstrated impressive efficacy when administered orally in a rat model of arthritis and in a mouse experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis.


Assuntos
Isoxazóis/síntese química , Isoxazóis/farmacologia , Lisofosfolipídeos/agonistas , Esfingosina/análogos & derivados , Animais , Artrite Experimental/tratamento farmacológico , Células CHO , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cricetinae , Cricetulus , Descoberta de Drogas , Encefalomielite Autoimune Experimental/tratamento farmacológico , Humanos , Imunossupressores/síntese química , Imunossupressores/farmacologia , Sistema Linfático/citologia , Sistema Linfático/efeitos dos fármacos , Linfócitos/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Ratos Endogâmicos Lew , Esfingosina/agonistas , Relação Estrutura-Atividade , Timo/citologia , Timo/efeitos dos fármacos
10.
ACS Med Chem Lett ; 7(1): 40-5, 2016 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-26819663

RESUMO

Efforts to identify a potent, reversible, nonsteroidal CYP17A1 lyase inhibitor with good selectivity over CYP17A1 hydroxylase and CYPs 11B1 and 21A2 for the treatment of castration-resistant prostate cancer (CRPC) culminated in the discovery of BMS-351 (compound 18), a pyridyl biaryl benzimidazole with an excellent in vivo profile. Biological evaluation of BMS-351 at a dose of 1.5 mg in castrated cynomolgus monkeys revealed a remarkable reduction in testosterone levels with minimal glucocorticoid and mineralcorticoid perturbation. Based on a favorable profile, BMS-351 was selected as a candidate for further preclinical evaluation.

11.
Anal Bioanal Chem ; 405(12): 4283-7, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23430183

RESUMO

PEGylation has been widely used to improve the biopharmaceutical properties of therapeutic proteins and peptides. Previous studies have used multiple analytical techniques to determine the fate of both the therapeutic molecule and unconjugated poly(ethylene glycol) (PEG) after drug administration. A straightforward strategy utilizing liquid chromatography-mass spectrometry (LC-MS) to characterize high-molecular weight PEG in biologic matrices without a need for complex sample preparation is presented. The method is capable of determining whether high-MW PEG is cleaved in vivo to lower-molecular weight PEG species. Reversed-phase chromatographic separation is used to take advantage of the retention principles of polymeric materials whereby elution order correlates with PEG molecular weight. In-source collision-induced dissociation (CID) combined with selected reaction monitoring (SRM) or selected ion monitoring (SIM) mass spectrometry (MS) is then used to monitor characteristic PEG fragment ions in biological samples. MS provides high sensitivity and specificity for PEG and the observed retention times in reversed-phase LC enable estimation of molecular weight. This method was successfully used to characterize PEG molecular weight in mouse serum samples. No change in molecular weight was observed for 48 h after dosing.


Assuntos
Cromatografia de Fase Reversa/métodos , Polietilenoglicóis/química , Animais , Espectrometria de Massas/métodos , Camundongos , Peso Molecular , Polietilenoglicóis/isolamento & purificação , Soro/química
12.
J Immunol Methods ; 384(1-2): 152-6, 2012 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-22750627

RESUMO

The effect of trough levels of a monoclonal antibody drug (drugB) on screening cut point (CP) determination for an anti-drug antibody (ADA) assay was scrutinized and the conclusions substantiated by data from a phase 3 cancer clinical study. The ADA assay utilized an acid dissociation step and either 0 or 100 µg/ml drugB was added to the samples prior to obtaining the signals used for CP calculations. Serum samples from three different drug-naive populations were tested (healthy individuals, cancer patients enrolled in the drugB clinical trial and cancer patients whose serum samples were available commercially). For the same disease state samples, both the screening CP and confirmation CP were different when calculated during validation or from study sample analysis. It is reasonable to assume that variability was due to the patient heterogeneity, as they could have been at distinct stages of disease progression, and/or taking different medications, amongst other differences. The patients enrolled in the clinical trial were stratified as per protocol and hence represented a more homogeneous population. Drug effects on CP may be population dependent and also assay dependent.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos/imunologia , Imunoensaio/normas , Neoplasias/imunologia , Anticorpos/sangue , Anticorpos Monoclonais/sangue , Anticorpos Monoclonais/uso terapêutico , Ensaios Clínicos como Assunto , Relação Dose-Resposta a Droga , Humanos , Imunoensaio/métodos , Cinética , Neoplasias/sangue , Neoplasias/tratamento farmacológico
13.
Drug Discov Today ; 16(1-2): 58-64, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21093608

RESUMO

Mass spectrometry (MS) has become a powerful technology in the discovery and development of protein therapeutics in the biopharmaceutical industry. This review article describes recent developments and future trends in the characterization of protein therapeutics using MS. We discuss top-down MS for the characterization of protein modifications, hydrogen/deuterium exchange MS and ion mobility MS methods for higher order protein structure studies. Quantitative analysis of protein therapeutics (in vivo) by MS as an orthogonal approach to immunoassay for pharmacokinetics studies will also be illustrated.


Assuntos
Descoberta de Drogas/métodos , Espectrometria de Massas/métodos , Proteínas/química , Proteínas/uso terapêutico , Descoberta de Drogas/tendências , Previsões , Humanos , Espectrometria de Massas/tendências , Proteínas/farmacocinética
14.
J Am Soc Mass Spectrom ; 21(5): 837-44, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20189823

RESUMO

Introduced in the late 1980s as a reducing reagent, Tris (2-carboxyethyl) phosphine (TCEP) has now become one of the most widely used protein reductants. To date, only a few studies on its side reactions have been published. We report the observation of a side reaction that cleaves protein backbones under mild conditions by fracturing the cysteine residues, thus generating heterogeneous peptides containing different moieties from the fractured cysteine. The peptide products were analyzed by high performance liquid chromatography and tandem mass spectrometry (LC/MS/MS). Peptides with a primary amine and a carboxylic acid as termini were observed, and others were found to contain amidated or formamidated carboxy termini, or formylated or glyoxylic amino termini. Formamidation of the carboxy terminus and the formation of glyoxylic amino terminus were unexpected reactions since both involve breaking of carbon-carbon bonds in cysteine.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Cisteína/química , Fragmentos de Peptídeos/química , Fosfinas/química , Proteínas/química , Espectrometria de Massas em Tandem/métodos , Cisteína/metabolismo , Concentração de Íons de Hidrogênio , Fragmentos de Peptídeos/metabolismo , Proteínas/metabolismo
15.
Drug Metab Dispos ; 38(4): 655-66, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20053818

RESUMO

The disposition of stavudine, a potent and orally active nucleoside reverse transcriptase inhibitor, was investigated in six healthy human subjects. Before dosing humans with [1'-(14)C]stavudine, a tissue distribution study was performed in Long-Evans rats. Results from this study showed no accumulation of radioactivity in any of the tissues studied, indicating that the position of the (14)C-label on the molecule was appropriate for the human study. After a single 80-mg (100 microCi) oral dose of [1'-(14)C]stavudine, approximately 95% of the radioactive dose was excreted in urine with an elimination half-life of 2.35 h. Fecal excretion was limited, accounting for only 3% of the dose. Unchanged stavudine was the major drug-related component in plasma (61% of area under the plasma concentration-time curve from time zero extrapolated to infinite time of the total plasma radioactivity) and urine (67% of dose). The remaining radioactivity was associated with minor metabolites, including mono- and bis-oxidized stavudine, glucuronide conjugates of stavudine and its oxidized metabolite, and an N-acetylcysteine (NAC) conjugate of the ribose (M4) after glycosidic cleavage. Formation of metabolite M4 was shown in human liver microsomes incubated with 2',3'-didehydrodideoxyribose, the sugar base of stavudine, in the presence of NAC. In addition, after similar microsomal incubations fortified with GSH, two GSH conjugates, 3'-GS-deoxyribose and 1'-keto-2',3'-dideoxy-3'-GS-ribose, were observed. This suggests that 2',3'-didehydrodideoxyribose underwent cytochrome P450-mediated oxidation leading to an epoxide intermediate, 2',3'-ribose epoxide, followed by GSH addition. In conclusion, absorption and elimination of stavudine were rapid and complete after oral dosing, with urinary excretion of unchanged drug as the predominant route of elimination in humans.


Assuntos
Fármacos Anti-HIV/farmacocinética , Estavudina/farmacocinética , Administração Oral , Animais , Fármacos Anti-HIV/administração & dosagem , Área Sob a Curva , Biotransformação , Cromatografia Líquida de Alta Pressão , Fezes/química , Humanos , Hidrólise , Técnicas In Vitro , Marcação por Isótopo , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Microssomos Hepáticos/metabolismo , Ratos , Ratos Long-Evans , Ribose/metabolismo , Estavudina/administração & dosagem , Distribuição Tecidual
16.
J Chromatogr B Analyt Technol Biomed Life Sci ; 877(5-6): 547-52, 2009 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-19185549

RESUMO

Unlike plasma and most biological fluids which have solute concentrations that are tightly controlled, urine volume can vary widely based upon water consumption and other physiological factors. As a result, the concentrations of endogenous metabolites in urine vary widely and normalizing for these effects is necessary. Normalization approaches that utilized urine volume, osmolality, creatinine concentration, and components that are common to all samples ("total useful MS signal") were compared in order to determine which strategies could be successfully used to differentiate between dose groups based upon the complete endogenous metabolite profile. Variability observed in LC/MS results obtained from targeted and non-targeted metabonomic analyses was highly dependent on the strategy used for normalization. We therefore recommend the use of two different normalization techniques in order to facilitate detection of statistically significant changes in the endogenous metabolite profile when working with urine samples.


Assuntos
Metabolômica/métodos , Urinálise/métodos , Animais , Creatinina/urina , Glicina/análogos & derivados , Glicina/urina , Hipuratos/urina , Concentração Osmolar , Análise de Componente Principal , Ratos , Ratos Sprague-Dawley , Padrões de Referência
17.
Curr Drug Metab ; 7(5): 547-55, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16787162

RESUMO

Fourier Transform Ion Cyclotron Mass Spectrometry (FTMS) provides the highest mass accuracy and mass resolving power of the currently available mass spectrometers. One of the main drawbacks in its use for absorption, distribution, metabolism and excretion (ADME) applications has been its incompatibility with standard HPLC columns and flow rates. Hybrid instruments, such as the LTQ-FT, provide the much needed bridge between the excellent performance and capabilities of the FT mass spectrometers and the well-established, tested and validated features of quadrupoles and ion traps. The hybrid instruments are compatible with standard HPLC flow rates, have high-throughput and automation compatibility, and also provide data dependant MSn. The ability to maintain the fidelity of an externally calibrated accurate mass measurement across an HPLC peak, where the analyte concentrations are rapidly changing, is a significant advance for this technology, as is the ability to perform data dependent MS/MS experiments on the chromatographic time scale. The MSn and accurate mass capabilities are routinely utilized to rapidly confirm the identification of expected metabolites or to elucidate the structures of unusual or unexpected metabolites. The combination of traditional high-flow chromatography and robust, externally calibrated accurate mass determination for both parent and product ions makes the LTQ-FTMS a very powerful analytical tool for the characterization of metabolites, identification of metabolic soft-spots and for metabonomics studies.


Assuntos
Biotransformação , Espectrometria de Massas , Preparações Farmacêuticas/metabolismo , Animais , Cromatografia Líquida de Alta Pressão/métodos , Análise de Fourier , Humanos , Espectrometria de Massas/métodos , Estrutura Molecular , Peso Molecular , Preparações Farmacêuticas/química , Reprodutibilidade dos Testes , Tecnologia Farmacêutica/métodos
18.
Anal Bioanal Chem ; 384(5): 1145-54, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16468024

RESUMO

Fluorescence detection has been a method of choice in industry for screening assays, including identification of enzyme inhibitors, owing to its high-throughput capabilities, excellent reproducibility, and sensitivity. Occasionally, inhibitors are identified that challenge the fluorescence assay limit, necessitating the development of more sensitive detection methods to assess these compounds. For data mining purposes, however, original assay conditions may be required. A direct method transfer to highly sensitive and specific LC-MS-based methods has not always been possible due to the presence of MS-incompatible neutral detergents and non-volatile salts in the assay matrix. Utilizing an in vitro proteolytic screening assay for the serine protease hepatitis C virus (HCV) nonstructural (NS) 3 protease as a test case, we report the development of an automated sample clean-up procedure implemented on-line with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to complement fluorescence detection. Ion exchange and peptide microtraps were employed to remove MS-incompatible assay matrix components. Three protease inhibitors were used to validate the MS/MS method. Comparable potencies were achieved for these compounds when assessed by fluorescence and MS/MS detection. Furthermore, four-fold less enzyme could be utilized when employing the MS/MS method compared to fluorescence detection. The longer analysis time, however, resulted in reduced sample capacity. The potency of our designed HCV NS3 protease inhibitors are thus routinely evaluated using a continuous fluorescence-based assay. Only pertinent inhibitors approaching the fluorescence assay sensitivity limit are subsequently analyzed further by LC-MS/MS. This methodology allows us to maintain a database and to compare results independent of the detection method. Despite the relatively slow sample turnaround time of this LC-MS approach, the versatility of the automated on-line clean-up procedure and sample analysis can be applied to assays containing reagents which were historically considered to be MS incompatible.


Assuntos
Espectrometria de Massas em Tandem/métodos , Proteínas não Estruturais Virais/análise , Cromatografia Líquida/métodos , Microscopia de Fluorescência/métodos , Estrutura Molecular , Sensibilidade e Especificidade
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