温暖与甜蜜

觉得热饮料更甜的道理得到了解释，加足了白糖的可可在热的时候非常甜，冰凉的可可就不怎么甜。这种感觉虽然谁都经历过，但原因始终是个谜。日本九州大学的研究组解释清楚了其中的道理，并且发表在2005年12月15日的《自然》杂志上——关键在于传递甜味信息的蛋白质。[编者按]     

去除后肢神经支配对大鼠骨骼肌中钠钾腺苷酶各亚基表达的影响

检测了去除神经支配的大鼠后肢和对侧的对照后肢骨骼肌中钠钾腺苷酶(Na—K—ATPase)各亚基的蛋白质和mRNA的表达，结果表明，去除后肢神经支配4d，在红色骨骼肌中α2和β1亚基的蛋白质表达显著下降(分别下降了46％和77％)，在红色腓肠肌和比目鱼肌中，α2亚基的mRNA水平分别下降了29％和39％，β1亚基的mRNA水平分别下降了80％和52％，在白色骨骼肌中α2亚基的蛋白质和mRNA水平无显著变化；在红色和白色骨骼肌中，α1亚基的蛋白质表达分别增加了20％和15％，同时伴随着更大幅度的mRNA水平的增加，而β2亚基的蛋白质表达未发生显著变化，其mRNA水平在红色腓肠肌中也无显著变化，但在白色腓肠肌中减少了59％．这些结果证实，在去除神经支配的大鼠骨骼肌中，钠钾腺苷酶各亚基的表达受转录和转录后调控，与已报道的胰岛素特异性诱导α2和β1亚基向细胞膜转移的研究结果相吻合．实验中仅α2和β1亚基的蛋白质表达显著下降暗示，在大鼠骨骼肌中，由于去除神经支配造成的胰岛素抵抗使原本受胰岛素调节的钠钾腺苷酶亚基的表达机制受到破坏．     

Inhibition of blue-light-dependent binding of 14-3-3 proteins to phototropins by hydrogen peroxide

Phototropins, following the discovery of phytochromes and cryptochromes, are the most recently characterized blue-light (BL) receptors in plants. The Nterminal regions of the proteins contain two light oxygen and voltage (LOV)--LOV1 and LOV2, which belong to PAS domain involved in protein-protein interaction and ligand binding,     

5种菌糖化发酵饲料对肉兔日粮中蛋白质利用率的影响

用5种菌(产朊假丝酵母、热带假丝酵母、啤酒酵母、黑曲霉、白地霉)糖化发酵饲料以20%比例部分替代肉兔日粮,对肉兔增质量、料质量比、蛋白质利用率及脏体比等各项指标进行比较分析.结果表明,5种菌糖化发酵饲料可以促进肉兔增质量,降低饲料消耗,提高肉兔日粮中蛋白质利用率,5种菌糖化发酵饲料的饲喂效果优于基础饲料.     

谷氨酰胺转移酶对食物蛋白质成膜性能的影响

研究了添加谷氨酰胺转移酶（TGase）对大豆分离蛋白（SPI）、酪蛋白酸（NaCN）、明胶、乳清蛋白浓缩物（WPC）、小麦面筋蛋白（WG）及花生分离蛋白（PPI）6种蛋白质成膜特性的影响．研究结果表明：在成膜溶液中加入TGase，蛋白质膜的抗拉强度和表面疏水性有不同程度的改善，其中WG，SPI，NaCN和明胶这4种蛋白质膜的抗拉强度分别增加36．2％，17．7％，13．1％和25．6％（P≤0．05）；NaCN，SPI，WPC，WG和明胶这5种蛋白质膜的表面疏水性分别增加216．1％，116．9％，30．5％，26．4％和2．4％（P≤0．05）；同时膜的水分含量、总可溶性物质量及透光率也明显降低；明胶膜、NaCN膜和WPC膜的断裂伸长率分别增加16．3％，72．6％和172．3％，SPI膜和WG膜的断裂伸长率则分别降低7．5％和36．2％．电泳分析表明TGase使6种蛋白质均产生了共价交联．     

基因抑制蛋白质揭示干细胞奥秘

科学家已经采取措施来揭示“干细胞性质”的奥秘:将对是什么促使胚胎干细胞(ES)能无休止地复制并保持其演变成为任何种类人体细胞的潜能作出解释。近期《细胞》和《自然》杂志上发表的论文称,保持干细胞特性的关键因素是称为多冠状聚合蛋白质的分子。美国麻省理工学院(MIT)和剑桥怀特黑德生物医学研究所的研究小组报道,这些蛋白质和其他蛋白质协同作用以抑制大部分调节基因(调节基因的蛋白质启动起关键作用的发育基因),使胚胎干细胞保持处于未分化状态。已知多冠状聚合蛋白质在诸如果蝇和人等不同生物体的发育上,都具有关键性的抑制基因的…     

The orientational preferences of backbones of proteins

The orientation between the backbone residues of proteins is defined based on the local configurations and the corresponding preferences are analyzed by statistics.It is found that all the residue pairs have some specific preferences of orientations.The statistical analysis is mainly concen-trated in the orientational distributions for two kinds of groupings of residues based on the hydrophobicity and secondary structural features.The statistics for such two types of groupings shows different orienta-tional preferences.It is found that for the former grouping the orientational preference is rather weak, while for the later a kind of strong orientational pref-erences.This suggests that the formation of local structures and of secondary structures are highly related to the orientational preferences.     

A Statistical Analysis of Protein—Protein Interaction with Knowledge—Based Potential at Residue Level

Protein-protein recognition is an important step in biological processes, which still largely remains elusive. The inter-residue contact potential, CPij, describes the propensity of contact between two types of residue. In this study, several different CPij variants were examined with the objective of discriminating the binding potential of surface pairs. Using solvent mediated inter-molecule contact potential (SM-IMCPij), an evaluation model was deduced and tested. Using the evaluation model it was found that the SM-IMCPij gives a better performance than either residue mediated IMCPij(RM-IMCPij) or folding-residue contact potential (FCPij). The results suggest that the evaluation model provides a fast, effective, and discriminative method for the evaluation of proposed binding interfaces.