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Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092
Published on: October 2, 2017
Role of carbohydrate moiety in carboxypeptidase Y: structural study of mutant enzyme lacking carbohydrate moiety
1Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Japan.
Abstract:
To study the roles of the carbohydrate moiety in the function of carboxypeptidase Y, asparagine residues at 13, 87, 168, and 368, the four-consensus N-linked glycosylation sites, were altered to alanine with site-directed mutagenesis. The mutant enzyme of 51 kDa completely lost the carbohydrate moiety which was present in the 61-kDa wild-type enzyme. Structural studies of the mutant enzyme showed that it maintained the native-like structure; hydrolytic activity, and substrate specificity of the mutant enzyme analogous to those of the wild-type enzyme. Susceptibility of the mutant enzyme toward proteolysis and pressure denaturation was reduced by 10-20%. It is concluded that the carbohydrate moiety functions to maintain the structural integrity of the enzyme under stressed.
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