Bošnjak I, Bojović V, Šegvić-Bubić T, Bielen A
Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, Pierottijeva 6, 10000 Zagreb, Croatia.
Protein Eng Des Sel. 2014 Mar;27(3):65-72. doi: 10.1093/protein/gzt063. Epub 2014 Jan 9.
Disulfide bonds (SS bonds) are important post-translational modifications of proteins. They stabilize a three-dimensional (3D) structure (structural SS bonds) and also have the catalytic or regulatory functions (redox-active SS bonds). Although SS bonds are present in all groups of organisms, no comparative analyses of their frequency in proteins from different domains of life have been made to date. Using the Protein Data Bank, the number and subcellular locations of SS bonds in Archaea, Bacteria and Eukarya have been compared. Approximately three times higher frequency of proteins with SS bonds in eukaryotic secretory organelles (e.g. endoplasmic reticulum) than in bacterial periplasmic/secretory pathways was calculated. Protein length also affects the SS bond frequency: the average number of SS bonds is positively correlated with the length for longer proteins (>200 amino acids), while for the shorter and less stable proteins (<200 amino acids) this correlation is negative. Medium-sized proteins (250-350 amino acids) indicated a high number of SS bonds only in Archaea which could be explained by the need for additional protein stabilization in hyperthermophiles. The results emphasize higher capacity for the SS bond formation and isomerization in Eukarya when compared with Archaea and Bacteria.
二硫键（SS键）是蛋白质重要的翻译后修饰。它们稳定三维（3D）结构（结构二硫键），也具有催化或调节功能（氧化还原活性二硫键）。尽管二硫键存在于所有生物类群中，但迄今为止尚未对来自不同生命域的蛋白质中二硫键的频率进行比较分析。利用蛋白质数据库，对古菌、细菌和真核生物中二硫键的数量和亚细胞定位进行了比较。计算得出，真核生物分泌细胞器（如内质网）中含有二硫键的蛋白质频率比细菌周质/分泌途径中的频率高约三倍。蛋白质长度也会影响二硫键频率：对于较长的蛋白质（>200个氨基酸），二硫键的平均数量与长度呈正相关，而对于较短且稳定性较差的蛋白质（<200个氨基酸），这种相关性为负。中等大小的蛋白质（250 - 350个氨基酸）仅在古菌中显示出大量二硫键，这可能是由于嗜热菌需要额外的蛋白质稳定性来解释。结果强调，与古菌和细菌相比，真核生物中二硫键形成和异构化的能力更强。
