Fate of 2‐sulphanylethyl acetate and 3‐sulphanylpropyl acetate through beer aging

Sulphanylalkyl alcohols and their corresponding acetates were investigated in 14 commercial Belgian beers. Although it was the major peak at the pulsed‐flame photometric detector, the empyreumatic 2‐sulphanylethyl acetate was found at concentrations below its individual odour threshold, estimated at 40 µg/L (0–4 µg/L in most fresh beers, 5–12 µg/L in three fresh high‐bitter beers). Both the Ehrlich pathway and hop constituents contribute to this content. In 11 of the investigated samples, synthesis of 2SE‐A and 3‐sulphanylpropyl acetate (roasted, burned) continued during the first three months of storage. Although below their individual thresholds, these compounds might interact by synergy with other aged flavours. As yeast was absent from most of the investigated bottles, chemical degradation of precursors is suspected. Copyright © 2012 The Institute of Brewing & Distilling     

The Portuguese Paradox: Why do some inhabitants of Portugal appear to live so long when their diet is based on whey cheese?

The remarkable longevity of people in specific regions of Portugal, whose diets are based on whey cheese, has puzzled researchers for quite some time. Our data indicate that several oligopeptides are released from glycomacropeptide (originated in κ-casein) and α-lactalbumin - and one surprisingly from β-lactoglobulin, by plant proteases previously used in cheesemaking. A few of such peptides (e.g. DKVGINYW, KGYGGVSLPEW and DAQSAPLRVY) exhibit unusually strong antihypertensive roles in vitro, following generation in situ or synthesis de novo. The activities of the latter two are not significantly affected by simulated gastrointestinal digestion, despite undergoing partial hydrolysis. This piece of information is rather promising toward more comprehensive attempts to scientifically rationalise this Portuguese Paradox.     

从适应低温的细菌中提取的低温酶（英）

从覆盖有积雪的土壤中的大麻哈鱼肠的螃蟹肠中分离出了新的细菌苗种,并对它们分泌出的淀粉酶、脂肪酶和蛋白酶的性能进行了研究。发现了一种淀粉酶、一种脂肪酶和三种蛋白酶,它们的最佳活性温度明显地朝低温方向移动,而且活化能有所降低。这些酶在高于最代温度（即３０℃￣４０℃）时迅速失活。结果表明,这些酶具有低温活性。低温活性最好的蛋白酶生产者从大麻哈鱼肠中分离出来的菌种通过１６Ｓｒ核糖核酸分析已验明为黄杆菌属,     

生物酶外加剂加固泥炭质软土的室内试验研究

采用一种国产生物蛋白酶和熟石膏粉作为外掺料,对黑色泥炭质水泥加固土进行了不同配比条件下3个龄期的加固土室内无侧限抗压强度的正交试验研究,对试验结果进行了方差和显著性分析,还进行了试块在硫酸钠溶液中浸泡的试验,验证了熟石膏粉和该种蛋白酶具有提高泥炭质水泥土试块强度的效果,试块具有一定的抗硫酸盐侵蚀的能力。     

PSNO: Predicting Cysteine S-Nitrosylation Sites by Incorporating Various Sequence-Derived Features into the General Form of Chou’s PseAAC

S-nitrosylation (SNO) is one of the most universal reversible post-translational modifications involved in many biological processes. Malfunction or dysregulation of SNO leads to a series of severe diseases, such as developmental abnormalities and various diseases. Therefore, the identification of SNO sites (SNOs) provides insights into disease progression and drug development. In this paper, a new bioinformatics tool, named PSNO, is proposed to identify SNOs from protein sequences. Firstly, we explore various promising sequence-derived discriminative features, including the evolutionary profile, the predicted secondary structure and the physicochemical properties. Secondly, rather than simply combining the features, which may bring about information redundancy and unwanted noise, we use the relative entropy selection and incremental feature selection approach to select the optimal feature subsets. Thirdly, we train our model by the technique of the k-nearest neighbor algorithm. Using both informative features and an elaborate feature selection scheme, our method, PSNO, achieves good prediction performance with a mean Mathews correlation coefficient (MCC) value of about 0.5119 on the training dataset using 10-fold cross-validation. These results indicate that PSNO can be used as a competitive predictor among the state-of-the-art SNOs prediction tools. A web-server, named PSNO, which implements the proposed method, is freely available at http://59.73.198.144:8088/PSNO/.     

Grassypeptolides as Natural Inhibitors of Dipeptidyl Peptidase 8 and T‐Cell Activation

Natural products made by marine cyanobacteria are often highly modified peptides and depsipeptides that have the potential to act as inhibitors for proteases. In the interests of finding new protease inhibition activity and selectivity, grassypeptolide A ( 1 ) was screened against a panel of proteases and found to inhibit DPP8 selectively over DPP4. Grassypeptolides were also found to inhibit IL‐2 production and proliferation in activated T‐cells, consistent with a putative role of DPP8 in the immune system. These effects were also observed in Jurkat cells, and DPP activity in Jurkat cell cytosol was shown to be inhibited by grassypeptolides. In silico docking suggests two possible binding modes of grassypeptolides—at the active site of DPP8 and at one of the entrances to the internal cavity. Collectively these results suggest that grassypeptolides might be useful tool compounds in the study of DPP8 function.     

Peptidyl Succinimidyl Peptides as Taspase 1 Inhibitors

Taspase 1 is an N‐terminal threonine protease implicated in leukemia and other cancers. Despite intensive efforts in recent years, only a limited number of Taspase 1 inhibitors are currently available, and they lack general applicability. Here we present a novel class of Taspase 1 inhibitors based on a peptidyl succinimidyl peptide motif. These inhibitors were obtained from the substrate cleavage sequence and mechanistic considerations involving the previously proposed asparaginase‐type cleavage mechanism. We anticipate that this class of Taspase 1 inhibitor will find wide application in further biochemical and structural studies, for example for better investigating the molecular details of the unusual enzymatic cleavage mechanism of Taspase 1.     

Effects of hydrophobic amino acid substitution in Pleurotus ostreatus proteinase A inhibitor 1 on its structure and functions as protease inhibitor and intramolecular chaperone

We previously demonstrated that Pleurotus ostreatus proteinase A inhibitor 1 (POIA1) could function as an intramolecular chaperone of subtilisin BPN', as in the case of the propeptide of subtilisin BPN', and that its Phe44 --> Ala mutant, which lost its tertiary structure, could not assist the refolding of subtilisin BPN'. In this study, we examined the effects of hydrophobic amino acid substitutions at other sites and substitutions of Phe44 with other hydrophobic residues on the structure and functions of POIA1. These mutations were introduced into POIA1cm that had been obtained by the substitution of the C-terminal six residues of POIA1 with those of the propeptide of subtilisin BPN'. When Ile32 or Ile64 was substituted with Ala, the tertiary structure of the resultant mutant was markedly destroyed, and the activities as a protease inhibitor and an intramolecular chaperone were significantly lowered. Among the position 44 mutants, the Phe44 --> Val mutant was a much less effective intramolecular chaperone with conversion to a digestible inhibitor, possibly owing to destruction of the tertiary structure. On the other hand, the Phe44 --> Leu or Ile mutant maintained its tertiary structure, and hence could function as a more effective intramolecular chaperone than the Phe44 --> Val mutant. Furthermore, since the Phe44 --> Leu mutant was a more susceptible inhibitor than POIA1cm, the halo formed around a colony of Bacillus cells transformed with a plasmid encoding this mutant was larger than others. These results clearly show the close relationship between the tertiary structure and functions of POIA1 as a protease inhibitor and an intramolecular chaperone, and that a combination of such inhibitory properties and intramolecular chaperone activity of POIA1 might affect the diameter of the halo formed around Bacillus colonies in vivo.