The prokaryotic serine protease

alpha-lytic protease (alpha LP) has done just that, as its unfolding is both very slow (t(1/2) similar to 1 year) and so cooperative that partial unfolding is negligible, providing a functional advantage over its thermodynamically stable homologs, such as trypsin. Previous studies have identified regions of the domain interface as critical to alpha LP unfolding, though a complete description of the unfolding pathway is missing. In order to identify the alpha LP unfolding pathway and the mechanism for its extreme cooperativity, we performed high temperature molecular dynamics unfolding simulations of both alpha LP and selleck products trypsin. The simulated alpha LP unfolding pathway produces a robust transition

state ensemble consistent with prior biochemical experiments and clearly shows that unfolding proceeds through a preferential disruption of the domain interface. Through a novel method of calculating unfolding cooperativity, we show that alpha LP unfolds extremely cooperatively while trypsin unfolds gradually. Finally, by examining the behavior of both domain interfaces, we propose a model for the differential unfolding cooperativity of alpha LP and trypsin involving three key regions that differ between the kinetically stable and thermodynamically stable classes of serine proteases.”
“Malaysia is a medium endemic CHIR98014 nmr country for hepatitis B virus (HBV) infection but little is known about HBV strains circulating in Malaysian blood donors. Viral load, HBsAg concentrations and nested PCR products from 84 HBV surface H 89 concentration antigen (HBsAg) positive samples were analysed in detail. Median viral load was 3050 IU/mL and median HBsAg 1150 IU/mL. Fifty-six full genome, 20 pre-S/S, 1 S gene and six

basic core promoter/precore-only sequences were obtained. Genotypes B and C were present at a ratio of 2:1, and two genotype D samples were obtained, both from donors of Indian background. Phylogenetically, genotype B was more diverse with subgenotypes B2-5, B7 and B8 present, while most genotype C strains were from subgenotype C1. Genotypes B and C were equally frequent in ethnic Malays, but 80% of strains from Chinese were genotype B. HBsAg concentrations were higher in genotype C than in genotype B, in Chinese than Malays and in donors under the age of 30. HBV vaccine escape substitutions (P120S/T, I126N and G145G) were present in six strains. In the large surface protein, immuno-inactive regions were more mutated than CD8 epitopes and the major hydrophilic region. Strains of genotype B or from ethnic Malays had higher genetic diversity than strains of genotype C or from Chinese donors. Hence HBV strains circulating in Malaysia are phylogenetically diverse reflecting the ethnic mix of its population.