beta-Glucosidase families revealed by computer analysis of protein sequences.

This computational study is a summary of how cloned beta-glucosidase subfamilies are organized. Computations were carried out using General Computer Group, Inc. (GCG) package programs. Twenty-two beta-glucosidases belonging to either cellulolytic or non-cellulolytic organisms were identified. The multialignment of a whole beta-glucosidase family is shown. Two sub-families, A and B, were clearly seen to exist. Sub-family A is further subdivided into sub-families A1 and A2. A1 includes vegetal beta-glucosidases and A2 includes prokaryotic enzymes. Sub-family B has three new sub-families, B1, B2, and B3. The enzymes in B2 are of yeast and/or fungi. Aspartic (D), glutamic (E) and histidine (H) residues, which are thought to be a part of the mechanism of the enzymatic hydrolysis are conserved. The well conserved amino acid sequences of the sub-family A are ITENGA; QUIEGA; HVD; and NEP. The well conserved amino acid sequences of the sub-family B are: SDW; and YN(R,K)(V,L)N.