Janecek S, Baláz S
Department of Biochemical Technology, Faculty of Chemical Technology, Slovak Technical University, Bratislava.
J Protein Chem. 1993 Oct;12(5):509-14. doi: 10.1007/BF01025115.
The parallel beta/alpha-barrel domain consisting of eight parallel beta-sheets surrounded by eight alpha-helices has been currently identified in crystal structures of more than 20 enzymes. This type of protein folding motif makes it possible to catalyze various biochemical reactions on a variety of substrates (i.e., it seems to be robust enough so that different enzymatic functionalities could be designed on it). In spite of many efforts aimed at elucidation of evolutionary history of the present-day beta/alpha-barrels, a challenging question remains unanswered: How has the parallel beta/alpha-barrel fold arisen? Although the complete sequence comparison of all beta/alpha-barrel amino acid sequences is not yet available, several sequence similarities have been revealed by using the highly conserved regions of alpha-amylase as structural templates. Since many starch-processing enzymes adopt the parallel beta/alpha-barrel structure these enzymes might be useful in the search for evolutionary relationships of the whole parallel eight-folded beta/alpha-barrel enzyme family.
目前已在20多种酶的晶体结构中鉴定出由八个平行β折叠片层被八个α螺旋包围组成的平行β/α桶状结构域。这种类型的蛋白质折叠基序使得催化各种底物上的各种生化反应成为可能（即，它似乎足够强大，以至于可以在其上设计不同的酶功能）。尽管为阐明当今β/α桶的进化历史付出了许多努力，但一个具有挑战性的问题仍然没有答案：平行β/α桶折叠是如何产生的？虽然尚未获得所有β/α桶氨基酸序列的完整序列比较，但通过使用α淀粉酶的高度保守区域作为结构模板，已经揭示了一些序列相似性。由于许多淀粉加工酶采用平行β/α桶结构，这些酶可能有助于寻找整个平行八重折叠β/α桶酶家族的进化关系。
