화학공학소재연구정보센터
Biochemical and Biophysical Research Communications, Vol.504, No.4, 647-653, 2018
Multiple mutations in the aglycone binding pocket to convert the substrate specificity of dalcochinase to linamarase
Dalcochinase from Dalbergia cochinchinensis Pierre and linamarase from Manihot esculenta Crantz are beta-glucosidases which share 47% sequence identity, but show distinct substrate specificities in hydrolysis and transglucosylation. Previously, three amino acid residues of dalcochinase, namely 1185, N189 and V255, were identified as being important for determining substrate specificity. In this study, kinetic analysis of the ensuing double and triple mutants of dalcochinase showed that only those containing the 185A mutation could appreciably hydrolyze linamarin as well as transfer glucose to 2-methyl-2-propanol. So, the space provided by the 1185A mutation appeared to be a prerequisite for accommodation of the aglycone moiety containing three substituents at the carbinol carbon. However, quantitative analysis of the energy parameters revealed mostly antagonistic interactions between these mutations. In addition, the N189F mutant showed a potential for use in enzymatic synthesis of alkyl glucosides via transglucosylation and reverse hydrolysis reactions. Thus, substitution of only 2-3 key residues in the aglycone binding pocket of dalcochinase could convert its specificities to that of linamarase, as well as to be suitable for any chosen hydrolytic or synthetic applications. (C) 2018 Elsevier Inc. All rights reserved.