Henrissat B, Callebaut I, Fabrega S, Lehn P, Mornon J P, Davies G
Centre de Recherches sur les Macromolécules Végétales, Centre National de la Recherche Scientifique, Grenoble, France.
Proc Natl Acad Sci U S A. 1995 Jul 18;92(15):7090-4. doi: 10.1073/pnas.92.15.7090.
The regions surrounding the catalytic amino acids previously identified in a few "retaining" O-glycosyl hydrolases (EC 3.2.1) have been analyzed by hydrophobic cluster analysis and have been used to define sequence motifs. These motifs have been found in more than 150 glycosyl hydrolase sequences representing at least eight established protein families that act on a large variety of substrates. This allows the localization and the precise role of the catalytic residues (nucleophile and acid catalyst) to be predicted for each of these enzymes, including several lysosomal glycosidases. An identical arrangement of the catalytic nucleophile was also found for S-glycosyl hydrolases (myrosinases; EC 3.2.3.1) for which the acid catalyst is lacking. A (beta/alpha)8 barrel structure has been reported for two of the eight families of proteins that have been grouped. It is suggested that the six other families also share this fold at their catalytic domain. These enzymes illustrate how evolutionary events led to a wide diversification of substrate specificity with a similar disposition of identical catalytic residues onto the same ancestral (beta/alpha)8 barrel structure.
先前在一些“保留型”O-糖基水解酶（EC 3.2.1）中鉴定出的催化氨基酸周围区域，已通过疏水簇分析进行了分析，并用于定义序列基序。这些基序已在150多个糖基水解酶序列中发现，这些序列代表至少八个已确定的蛋白质家族，它们作用于多种底物。这使得能够预测这些酶中每一种的催化残基（亲核试剂和酸催化剂）的定位和精确作用，包括几种溶酶体糖苷酶。对于缺乏酸催化剂的S-糖基水解酶（黑芥子酶；EC 3.2.3.1），也发现了催化亲核试剂的相同排列。已报道在已归类的八个蛋白质家族中的两个家族中存在（β/α）8桶状结构。有人提出，其他六个家族在其催化结构域也具有这种折叠。这些酶说明了进化事件是如何导致底物特异性广泛多样化的，同时相同的催化残基以相似的方式分布在相同的祖先（β/α）8桶状结构上。
