Barrett A J, Rawlings N D
Department of Biochemistry, Strangeways Research Laboratory, Cambridge, United Kingdom.
Arch Biochem Biophys. 1995 Apr 20;318(2):247-50. doi: 10.1006/abbi.1995.1227.
It has become clear that the proteolytic enzymes that depend upon a serine residue for their catalytic activity belong to many different families of proteins. We have attempted to group these families in "clans." A clan is defined as a group of families the members of which have a common ancestor. That is to say, they are homologous, although some of the similarities are in the "twilight zone" and the relationships cannot be proven by rigorous statistical methods. We believe we can recognize five, or perhaps six, clans of serine peptidases. In view of the separate evolutionary origins of the serine peptidases in different clans, it is not surprising to find that they may differ greatly and that indeed there are few generalizations that can be applied to all serine peptidases. In contrast, the members of a clan commonly have marked similarities.
很明显，那些依赖丝氨酸残基发挥催化活性的蛋白水解酶属于许多不同的蛋白质家族。我们试图将这些家族归为“族”。一个族被定义为一组家族，其成员有共同的祖先。也就是说，它们是同源的，尽管有些相似性处于“模糊地带”，且这些关系无法通过严格的统计方法得到证实。我们认为可以识别出五个，或许六个丝氨酸肽酶族。鉴于不同族中丝氨酸肽酶的进化起源不同，发现它们可能差异很大，而且确实很少有适用于所有丝氨酸肽酶的普遍规律，这并不奇怪。相比之下，一个族的成员通常有显著的相似性。
