Assessment of structural behaviour of a new L-asparaginase and SAXS data-based evidence for catalytic activity in its monomeric form.

The present study reports the structural and functional characterization of a new glutaminase-free recombinant L-asparaginase (PrASNase) from Pseudomonas resinovorans IGS-131. PrASNase showed substrate specificity to L-asparagine, and its kinetic parameters, Km, Vmax, and kcat were 9.49 × 10-3 M, 25.13 IUmL-1 min-1, and 3.01 × 103 s-1, respectively. The CD spectra showed that PrASNase consisted of 18.5 % helix, 21.5 % antiparallel sheets, 4.2 % parallel sheets, 14 % turns, and rest other structures. FTIR was used for the functional characterization, and molecular docking predicted that the substrate interacts with serine, alanine, and glutamine in the binding pocket of PrASNase. Differing from known asparaginases, structural characterization by small-angle X-ray scattering (SAXS) and analytical ultracentrifugation (AUC) unambiguously revealed PrASNase to exist as a monomer in solution at low temperatures and oligomerized to a higher state with temperature rise. Through SAXS studies and enzyme assay, PrASNase was found to be mostly monomer and catalytically active at 37 °C. Furthermore, this glutaminase-free PrASNase showed killing effects against WIL2-S and TF-1.28 cells with IC50 of 7.4 µg.mL-1 and 5.6 µg.mL-1, respectively. This is probably the first report with significant findings of fully active L-asparaginase in monomeric form using SAXS and AUC and demonstrated the potential of PrASNase in inhibiting cancerous cells, making it a potential therapeutic candidate.

Wild soybean salt tolerance metabolic model: Assessment of storage protein mobilization in cotyledons and C/N balance in the hypocotyl/root axis.

Salt stress has become one of the main factors limiting crop yield in recent years. The post-germinative growth is most sensitive to salt stress in soybean. In this study, cultivated and wild soybeans were used for an integrated metabonomics and transcriptomics analysis to determine whether wild soybean can resist salt stress by maintaining the mobilization of stored substances in cotyledons and the balance of carbon and nitrogen in the hypocotyl/root axis (HRA). Compared with wild soybean, the growth of cultivated soybean was significantly inhibited during the post-germinative growth period under salt stress. Integrating analysis found that the breakdown products of proteins, such as glutamate, glutamic acid, aspartic acid, and asparagine, increased significantly in wild soybean cotyledons. Asparagine synthase and fumarate hydratase genes and genes encoding HSP20 family proteins were specifically upregulated. In wild soybean HRA, levels of glutamic acid, aspartic acid, asparagine, citric acid, and succinic acid increased significantly, and the glutamate decarboxylase gene and the gene encoding carbonic anhydrase in nitrogen metabolism were significantly upregulated. The metabolic model indicated that wild soybean enhanced the decomposition of stored proteins and the transport of amino acids to the HRA in cotyledons and the GABA shunt to maintain carbon and nitrogen balance in the HRA to resist salt stress. This study provided a theoretical basis for cultivating salt-tolerant soybean varieties and opened opportunities for the development of sustainable agricultural practices.

A bias of Asparagine to Lysine mutations in SARS-CoV-2 outside the receptor binding domain affects protein flexibility.

Introduction: COVID-19 pandemic has been threatening public health and economic development worldwide for over two years. Compared with the original SARS-CoV-2 strain reported in 2019, the Omicron variant (B.1.1.529.1) is more transmissible. This variant has 34 mutations in its Spike protein, 15 of which are present in the Receptor Binding Domain (RBD), facilitating viral internalization via binding to the angiotensin-converting enzyme 2 (ACE2) receptor on endothelial cells as well as promoting increased immune evasion capacity. Methods: Herein we compared SARS-CoV-2 proteins (including ORF3a, ORF7, ORF8, Nucleoprotein (N), membrane protein (M) and Spike (S) proteins) from multiple ancestral strains. We included the currently designated original Variant of Concern (VOC) Omicron, its subsequent emerged variants BA.1, BA2, BA3, BA.4, BA.5, the two currently emerging variants BQ.1 and BBX.1, and compared these with the previously circulating VOCs Alpha, Beta, Gamma, and Delta, to better understand the nature and potential impact of Omicron specific mutations. Results: Only in Omicron and its subvariants, a bias toward an Asparagine to Lysine (N to K) mutation was evident within the Spike protein, including regions outside the RBD domain, while none of the regions outside the Spike protein domain were characterized by this mutational bias. Computational structural analysis revealed that three of these specific mutations located in the central core region, contribute to a preference for the alteration of conformations of the Spike protein. Several mutations in the RBD which have circulated across most Omicron subvariants were also analysed, and these showed more potential for immune escape. Conclusion: This study emphasizes the importance of understanding how specific N to K mutations outside of the RBD region affect SARS-CoV-2 conformational changes and the need for neutralizing antibodies for Omicron to target a subset of conformationally dependent B cell epitopes.

Potential of Low Cost Agro-Industrial Wastes as a Natural Antioxidant on Carcinogenic Acrylamide Formation in Potato Fried Chips.

Acrylamide is classified as a toxic and a prospective carcinogen to humans, and it is formed during thermal process via Maillard reaction. In order to find innovative ways to diminish acrylamide formation in potato chips, several extracts of agricultural wastes including potato peels, olive leaves, lemon peels and pomegranate peels extracts were examined as a soaking pre-treatment before frying step. Total phenolic, total flavonoids, antioxidant activity, and the reduction in sugar and asparagine contents were additionally performed. Proximate composition of these wastes was found to be markedly higher in fat, carbohydrate and ash contents. Lemon peels and potato peels showed almost similar phenolic content (162 ± 0.93 and 157 ± 0.88 mg GAE /g, respectively) and exhibited strong ABTS and DPPH radical scavenging activities than the other wastes. The reduction percentage of reducing sugars and asparagine after soaking treatment ranged from 28.70 to 39.57% and from 22.71 to 29.55%, respectively. HPLC results showed higher level of acrylamide formation in control sample (104.94 mg/kg) and by using the wastes extracts of lemon peels, potato peels, olive leaves, and pomegranate peels succeeded to mitigate acrylamide level by 86.11%, 69.66%, 34.03%, and 11.08%, respectively. Thus, it can be concluded that the soaking of potato slices in the tested wastes extracts as antioxidant as pre-treatment before frying reduces the formation of acrylamide and in this way, the risks connected to acrylamide consumption could be regulated and managed.

L-asparaginase from Dickeya chrysanthemi: expression, purification and cytotoxicity assessment.

Microbial L-asparaginases are aminohydrolases that hydrolyze L-asparagine to L-aspartate. They are used to treat acute lymphoblastic leukemia and Hodgkin's lymphomas and in food industries. Increasing demand for L-ASNases is therefore needed. In the current study, the recombinant L-ASNase from Dickeya chrysanthemi (DcL-ASNase) was cloned into pET28a (+) expression vector and expressed in Escherichia coli as a 6His-tagged fusion protein and purified using Ni2+ chelated Sepharose chromatography resin, yielding a highly purified enzyme. Kinetics analysis allowed the determination of its substrate specificity and the physicochemical parameters that affect enzyme activity. The enzyme showed operational stability at 37 °C and 45 °C. The immunogenicity of the purified DcL-ASNase was evaluated by measuring the IgG and IgM levels in rats after injection. The cytotoxicity DcL-ASNase in selected cancer cell lines and peripheral blood monocytes was determined. The results showed that the enzyme induces pleiotropic effects, including significant morphological changes and the formation of apoptotic bodies. No cytotoxic effects were observed in peripheral blood monocytes at the same concentrations. In addition, gene expression analysis by RT-PCR of apoptotic biomarkers (Bax, survivin, and Ki-67) allowed the study of the apoptotic mechanism induced by DcL-ASNase on THP-1 cells.

Assessment method for deamidation in proteins using carboxylic acid derivatization-liquid chromatography-tandem mass spectrometry.

An analytical method for the degree of protein deamidation has been developed by using carboxy group derivatization and liquid chromatography-tandem mass spectrometry (LCMS/MS). The fragment peptides (LGEYGFQNALIVR and YNGVFQECCQAEDK) obtained by digesting bovine serum albumin (BSA) with trypsin and their asparagine deamidated peptides (LGEYGFQDALIVR and YDGVFQECCQAEDK) were selected as model peptides, and their carboxy groups were derivatized with ethylamine. This derivatization enabled a clear distinction between natural peptides and deamidated peptides by mass, allowing for facile distinction by LCMS/MS before and after deamidation. Good linearity was confirmed for four peptides used in this study via isotope dilution mass spectrometry, showing that protein deamidation can be evaluated by the present method. To confirm the validity of this method for the evaluation of deamidation, natural peptides and deamidated peptides were mixed in arbitrary ratios, and degree of deamidation in these solution was analyzed. This confirmed that accurate evaluation was possible at deamidation degree values of ca. 10 %, 5 %, 2.5 %, and 1 %. Additionally, an accelerated storage test of BSA demonstrated that the deamidation of asparagine at position 404 of BSA progressed by 4 % in 9 weeks at 40 °C and pH 8 in the dark, and that the deamidation process can be traced over time.

High throughput detection of deamidation using S-(5'-adenosyl)-l-homocysteine hydrolase and a fluorogenic reagent.

Deamidation of asparagine (Asn) residues is one of the most common chemical degradation pathways observed in proteins. This reaction must be understood and controlled in therapeutic drug candidates, as chemical changes can affect their efficacy and safety. The analytical tools available for detection of deamidation reaction products, such as isoaspartic acid residues, are either chromatographic or electrophoretic, and require MS detection for absolute identification of peaks. High-throughput measurement of protein degradation has typically been limited to probing the target's physical state using spectroscopic techniques. Here, we describe a high throughput assay for isoaspartate residues using fluorescent detection in a microtiter plate format. The method allows for fast detection of protein deamidation in a cost-efficient manner. The method can be employed even if the target peptide or protein contains free Cys residues. The technique appears to be selective, linear, and accurate.

Quantitative assessment of mAb Fc glycosylation of CQA importance by capillary electrophoresis.

The attached carbohydrates at the highly conserved asparagine-linked glycosylation site in the CH 2 domain of the fragment crystallizable (Fc) region of monoclonal antibody therapeutics can play an essential role in their mechanism of action, including ADCC, CDC, anti-inflammatory functions, and serum half-life. Thus, this particular glycosylation represents one of the important critical quality attributes (CQA) of therapeutic monoclonal antibodies, which should be closely monitored and controlled during all stages of biopharmaceutical manufacturing. To study Fc glycosylation related quantitative critical quality attributes, the N-glycan pool of adalimumab (Humira® ) was spiked with increasing amounts of mannose-5 oligosaccharide, a glycan with high CQA importance. The method enabled precise quantitative CQA assessment with high detection sensitivity.

Eficacia y seguridad de L-asparaginasa erwinia y L-asparaginasa E. Coli pegilada en el tratamiento de pacientes con leucemia linfoblástica aguda que presentam hipersensibilidad a L-asparaginasa E. coli nativa / Efficacy and safety of L-asparaginase erwinia and L-asparaginase E. coli pegylated in the treatment of patients with acute lymphoblastic leukemia who are hypersensitive to L-asparaginase E. coli native

INTRODUÇÃO: Antecedentes: El presente dictamen expone la evaluación de tecnología de la eficacia y seguridad del uso de L-asparaginasa Erwinia y L-asparaginasa E. coli pegilada para el tratamiento de pacientes con leucemia linfoblástica aguda que presentan hipersensibilidad a L-asparaginasa E. coli nativa. Aspectos Generales: La leucemia es el tipo de cáncer más común en niños, representando aproximadamente el 30% de todos los tipos de cáncer diagnosticados en niños; siendo la leucemia linfoblástica aguda (LLA) uno de los dos tipos de leucemias más comunes. Adicionalmente, alrededor del 60% de todos los casos de LLA ocurre en pacientes menores de 20 años. Así, LLA es un tipo de leucemia de alta importancia dentro de población joven. Tecnología Sanitaria de Interés: Las células neoplásicas en la leucemia linfoblástica aguda (LLA) no sintetizan las cantidades necesarias del aminoácido L-asparagina; por lo que requieren de funtes externas (i.e., L-asparagina extracelular). La L-asparaginasa, es una enzima que cataliza la conversión de L-asparagina más agua, en ácido aspártico y amoniaco, ocasionando que los niveles de L-asparagina extracelular disminuyan; y que por los tanto las células d ela LLA no cuenten con L-asparagina extracelular. Así, estas células neoplásicas se quedan sin fuentes de L-asparagina, y no pueden sintetizar proteínas de gran imporancia para su supervivencia, ocasionando su muerte. METODOLOGÍA: Estrategia de Búsqueda: Se realizó una búsqueda de la literatura a la eficacia y seguridad del uso de L-asparaginasa Erwinia y L-asparaginasa E. coli pegilada para el tratamiento de pacientes niños y adultos con leucemia linfoblástica aguda que presentan hipersensibilidad a L-asparaginasa E. coli nativa. Esta búsqueda se realizó utilizando los meta-buscadores: Translating Research into Practice (TRIPDATABASE) Y National Library of Medicine (Pubmed-Medline). RESULTADOS: Sinopsis de la Evidencia: Se realizó la búsqueda bibliográfica y de evidencia científica hasta marzo del 2017 para el sustento del uso de L-asparaginasa Erwinia en el tratamiento de leucemia linfoblástica aguda en pacientes niños y adultos que presentan hipersensibilidad a L-asparaginasa E. coli nativa. Se presente la evidencia disponible según el tipo de publicación priorizada en los criterios de inclusión (i.e., GP, ETS, RS y ECA fase III), siendo los ensayos de fase III o en su defecto ensayos controlados y aleatorizados la principal considerada. CONCLUSIONES: El presente dictamen evaluó la mejor evidencia disponible hasta marco 2017 en relación al uso de L-asparaginasa Erwinia y L-asparaginasa E. coli pegilada para el tratamiento de pacientes niños, adolescentes, y adultos con leucemia linfoblástica aguda, que presentan hipersensibilidad a L-asparaginasa E. coli nativa. El Instituto de Tecnologías Sanitarias-IETSI, aprueba el uso de L-asparaginasa Erwinia como parte del esquema quimioterápico utilizada para el tratamiento de pacientes niños, adolescentes, y adultos con leucemia linfoblástica aguda, que presentan hipersensibilidad grado 2 o más a L-asparaginasa E. coli nativa. La vigencia de este dictamen preliminar es de dos años a partir de la fecha de publicación. Asimismo, el Instituto de Tecnologías Sanitarias-IETSI, no aprueba el uso de L-asparaginasa E. coli pegilada en el tratamiento de pacientes niños, adolescentes, y adultos con leucemia linfoblástica aguda, que presentan hipersensiblidad grado 2 o más a L-asparaginasa E. coli nativa.

Reduction in Dietary Acrylamide Exposure-Impact of Potatoes with Low Acrylamide Potential.

Acrylamide forms primarily from a reaction between reducing sugars (e.g., glucose and fructose) and an amino acid (asparagine, Asn) formed naturally in foods, including potatoes. This reaction occurs when carbohydrate-rich foods are heated at temperatures above 120 °C. Multiple potato varieties were transformed with potato genomic DNA that results in down-regulation of the expression of the asparagine synthetase-1 gene (Asn1), significantly reducing synthesis of free Asn, and consequently lowering the potential to form acrylamide during cooking. These potatoes with low acrylamide potential (LAP) were tested in agronomic trials, and processed into French fries and potato chips. Decreased levels of acrylamide were measured in these cooked food products when derived from LAP potatoes compared with those derived from conventional potatoes. These reductions can be directly attributed to reduction in Asn levels in the LAP potatoes. The corresponding average reduction in exposure to acrylamide from French fry and potato chip consumption is estimated to be 65%, which would amount to approximately a 25% reduction in overall dietary exposure. Considering that children consume nearly three times more acrylamide than adults on a per kg body weight basis, they would experience the most impact from the reduced acrylamide associated with LAP potatoes. The potential public health impacts, in context of dietary acrylamide exposure reduction, are discussed in this study.

Investigation of asparagine deamidation in a SOD1-based biosynthetic human insulin precursor by MALDI-TOF mass spectrometry.

A biosynthetic human insulin precursor displayed enhanced susceptibility to deamidation at one particular site. The present study was undertaken to monitor progress of precursor deamidation at successive manufacturing stages. MALDI-TOF/TOF MS in combination with controlled endoproteinase Glu-C and endoproteinase Asp-N proteolysis was used for rapid and unambiguous determination of deamidated residue within the investigated structure. Close inspection of isotopic distribution patterns of peptides resulting from enzymatic digestion enabled determination of distinct precursor forms occurring during the production process. Asn, Asp, isoAsp and succinimide derivatives of the amino acid at position 26 were unambiguously identified. These modifications are related to the leader peptide of a precursor encompassing amino acid sequence corresponding to that of superoxide dismutase [Cu-Zn] (SOD1 1, EC=1.15.1.1). Monitoring of precursor deamidation process at successive manufacturing stages revealed that the protein folding stage was sufficient for a prominent replacement of asparagine by aspartic and isoaspartic acid and the deamidated human insulin precursor constituted the main manufactured product. Conversion proceeded through a succinimide intermediate. Significant deamidation is associated with the presence of SNG motif and confirms results achieved previously on model peptides. Our findings highlight an essential role of the specific amino acid sequence on accelerated rate of protein deamidation. To our knowledge, this is the first time that such a dramatic change in the relative abundance of Asp and isoAsp resulting from protein deamidation process is reported.

Risk assessment, formation, and mitigation of dietary acrylamide: current status and future prospects.

Acrylamide (AA) was firstly detected in food in 2002, and since then, studies on AA analysis, occurrence, formation, toxicity, risk assessment and mitigation have been extensively carried out, which have greatly advanced understanding of this particular biohazard at both academic and industrial levels. There is considerable variation in the levels of AA in different foods and different brands of the same food; therefore, so far, a general upper limit for AA in food is not available. In addition, the link of dietary AA to human cancer is still under debate, although AA has been known as a potential cause of various toxic effects including carcinogenic effects in experimental animals. Furthermore, the oxidized metabolite of AA, glycidamide (GA), is more toxic than AA. Both AA and GA can form adducts with protein, DNA, and hemoglobin, and some of those adducts can serve as biomarkers for AA exposure; their potential roles in the linking of AA to human cancer, reproductive defects or other diseases, however, are unclear. This review addresses the state-of-the-art understanding of AA, focusing on risk assessment, mechanism of formation and strategies of mitigation in foods. The potential application of omics to AA risk assessment is also discussed.

Current issues in dietary acrylamide: formation, mitigation and risk assessment.

Acrylamide (AA) is known as a neurotoxin in humans and it is classified as a probable human carcinogen by the International Agency of Research on Cancer. AA is produced as by-product of the Maillard reaction in starchy foods processed at high temperatures (>120 °C). This review includes the investigation of AA precursors, mechanisms of AA formation and AA mitigation technologies in potato, cereal and coffee products. Additionally, most relevant issues of AA risk assessment are discussed. New technologies tested from laboratory to industrial scale face, as a major challenge, the reduction of AA content of browned food, while still maintaining its attractive organoleptic properties. Reducing sugars such as glucose and fructose are the major contributors to AA in potato-based products. On the other hand, the limiting substrate of AA formation in cereals and coffee is the free amino acid asparagine. For some products the addition of glycine or asparaginase reduces AA formation during baking. Since, for potatoes, the limiting substrate is reducing sugars, increases in sugar content in potatoes during storage then introduce some difficulties and potentially quite large variations in the AA content of the final product. Sugars in potatoes may be reduced by blanching. Levels of AA in different foods show large variations and no general upper limit is easily applicable, since some formation will always occur. Current policy is that practical measures should be taken voluntarily to reduce AA formation in vulnerable foods since AA is considered a health risk at the concentrations found in foods.

Simultaneous assessment of Asp isomerization and Asn deamidation in recombinant antibodies by LC-MS following incubation at elevated temperatures.

The degradation of proteins by asparagine deamidation and aspartate isomerization is one of several chemical degradation pathways for recombinant antibodies. In this study, we have identified two solvent accessible degradation sites (light chain aspartate-56 and heavy chain aspartate-99/101) in the complementary-determining regions of a recombinant IgG1 antibody susceptible to isomerization under elevated temperature conditions. For both hot-spots, the degree of isomerization was found to be significantly higher than the deamidation of asparagine-(387, 392, 393) in the conserved CH3 region, which has been identified as being solvent accessible and sensitive to chemical degradation in previous studies. In order to reduce the time for simultaneous identification and functional evaluation of potential asparagine deamidation and aspartate isomerization sites, a test system employing accelerated temperature conditions and proteolytic peptide mapping combined with quantitative UPLC-MS was developed. This method occupies the formulation buffer system histidine/HCl (20 mM; pH 6.0) for denaturation/reduction/digestion and eliminates the alkylation step. The achieved degree of asparagine deamidation and aspartate isomerization was adequate to identify the functional consequence by binding studies. In summary, the here presented approach greatly facilitates the evaluation of fermentation, purification, formulation, and storage conditions on antibody asparagine deamidation and aspartate isomerization by monitoring susceptible marker peptides located in the complementary-determining regions of recombinant antibodies.

Assessment of D216H DYT1 polymorphism in a Chinese primary dystonia patient cohort.

BACKGROUND: The D216H single-nucleotide polymorphism (SNP) (rs1801968) in DYT1 exon 4 has been suggested to be a genetic modifier in primary dystonia. METHODS: To further explore this question, we assessed rs1801968 variations in a cohort of 210 Chinese patients with primary dystonia devoid of DYT1 mutations. RESULTS: We found that focal dystonia, specifically cervical dystonia, was the most common form of dystonia, with 8.1% of all the patients having a positive family history of dystonia. No association of the D216H SNP with primary dystonia was identified. In a subsequent subgroup analysis, the 216H allele was found to occur more frequently in patients with writer's cramp, but no correlation was found between the allele and other forms of dystonia or age of onset. CONCLUSIONS: Our findings do not confirm that the allele contributes to the risk of D216H SNP primary dystonia.

An economical method for producing stable-isotope labeled proteins by the E. coli cell-free system.

Improvement of the cell-free protein synthesis system (CF) over the past decade have made it one of the most powerful protein production methods. The CF approach is especially useful for stable-isotope (SI) labeling of proteins for NMR analysis. However, it is less popular than expected, partly because the SI-labeled amino acids used for SI labeling by the CF are too expensive. In the present study, we developed a simple and inexpensive method for producing an SI-labeled protein using Escherichia coli cell extract-based CF. This method takes advantage of endogenous metabolic conversions to generate SI-labeled asparagine, glutamine, cysteine, and tryptophan, which are much more expensive than the other 16 kinds of SI-labeled amino acids, from inexpensive sources, such as SI-labeled algal amino acid mixture, SI-labeled indole, and sodium sulfide, during the CF reaction. As compared with the conventional method employing 20 kinds of SI-labeled amino acids, highly enriched uniform SI-labeling with similar labeling efficiency was achieved at a greatly reduced cost with the newly developed method. Therefore, our method solves the cost problem of the SI labeling of proteins using the CF.

Topological assessment of oatp1a1: a 12-transmembrane domain integral membrane protein with three N-linked carbohydrate chains.

Organic anion transport protein 1a1 (oatp1a1), a prototypical member of the oatp family of highly homologous transport proteins, is expressed on the basolateral (sinusoidal) surface of rat hepatocytes. The organization of oatp1a1 within the plasma membrane has not been well defined, and computer-based models have predicted possible 12- as well as 10-transmembrane domain structures. Which of oatp1a1's four potential N-linked glycosylation sites are actually glycosylated and their influence on transport function have not been investigated in a mammalian system. In the present study, topology of oatp1a1 in the rat hepatocyte plasma membrane was examined by immunofluorescence analysis using an epitope-specific antibody designed to differentiate a 10- from a 12-transmembrane domain model. To map glycosylation sites, the asparagines at the each of the four N-linked glycosylation consensus sites were mutagenized to glutamines. Mutagenized oatp1a1 constructs were expressed in HeLa cells, and effects on protein expression and transport activity were assessed. These studies revealed that oatp1a1 is a 12-transmembrane-domain protein in which the second and fifth extracellular loops are glycosylated at asparagines 124, 135, and 492, whereas the potential glycosylation site at asparagine 62 is not utilized, consistent with its position in a transmembrane domain. Constructs in which more than one glycosylation site were eliminated had reduced transport activity but not necessarily reduced transporter expression. This was in accord with the finding that fully unglycosylated oatp1a1 was well expressed but located intracellularly with limited transport ability as a consequence of its reduced cell surface expression.

Endothelin-1 gene Lys198Asn polymorphism and blood pressure reactivity.

The Lys198Asn polymorphism of the endothelin-1 gene has been associated with increased blood pressure levels in several studies involving European and Australian adults. The purpose of the present study was to examine the potential moderating influence of ethnicity, obesity, and socioeconomic status on associations between the ET-1/Lys198Asn polymorphism and hemodynamic function at rest and during two laboratory stressors (video game, forehead cold) in a sample of 161 black and 213 white American normotensive young adults (mean age, 18.5+/-2.7 years). Carrier status of the T allele was not associated with resting blood pressure or total peripheral resistance index. However, carriers of the T allele showed greater diastolic blood pressure increases to the video game (P<0.04), particularly among those who were obese (P<0.02). Carrier status also interacted with socioeconomic status such that T allele carriers who came from lower socioeconomic status backgrounds exhibited the greatest increases in systolic blood pressure to the video game challenge (P<0.05). In conclusion, the findings point out the importance of examining the impact of genetic polymorphisms on blood pressure control phenotypes within the context of potentiating environmental factors.

Thermodynamical properties of simple models of protein-like heteropolymers.

The lattice approximation of a heteropolymer chain as a model of a single polypeptide was used in the computer simulation. The residues of a model polypeptide were represented by the chain of alpha-carbons located on a very flexible [310] lattice. The force field that mimic the intramolecular interactions contained the long-range contact potential between the residues and the local preferences in forming helical structures. The chain consisted of two types of residues that had different hydrophobicity. The simulations were performed by means of the Replica Exchange Monte Carlo method combined with the Histogram method. The series of simulations were carried out to investigate the influence of both components of the force field on the transition temperature and the characteristics of the coil-to-globule transition. The properties of low-temperature ordered structures were determined. The thermodynamical description of the model chain was also given. The phase transition was found to be sharp and cooperative for longer chains and strong helical potential. The collapsed globule contained the strongly hydrophobic residues inside the globule while the remaining residues were mainly located close to the globule surface.