Site-directed mutation of β-galactosidase from Aspergillus candidus to reduce galactose inhibition in lactose hydrolysis.

ABSTRACT: β-Galactosidase is widely used for hydrolysis of whey lactose. However, galactose inhibition has acted as a major constraint on the catalytic process. Thus, it is sensible to improve upon this defect in β-galactosidase through protein modification. To reduce the galactose inhibition of Aspergillus candidus β-galactosidase (LACB), four amino acid positions were selected for mutation based on their molecular bindings with galactose. Four mutant libraries (Tyr96, Asn140, Glu142, and Tyr364) of the LACB were constructed using site-directed mutagenesis. Among all of the mutants, Y364F was superior to the wild-type enzyme. The Y364F mutant has a galactose inhibition constant (K _i) of 282 mM, 15.7-fold greater than that of the wild-type enzyme (K _i = 18 

SUBMITTER: Zhang Z 

PROVIDER: S-EPMC6191392 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature