Role of Tyr-435 of <Emphasis Type="Italic">Vibrio harveyi</Emphasis> Chitinase A in Chitin Utilization |
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Authors: | Natchanok Sritho Wipa Suginta |
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Institution: | (1) Biochemistry-Electrochemistry Research Unit, Schools of Chemistry and Biochemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, 30000, Thailand; |
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Abstract: | Vibrio harveyi chitinase A or VhChiA (EC.3.2.1.14) is a member of GH-18 chitinases that catalyzes chitin degradation from marine biomaterials. Our earlier
structural data of VhChiA suggested that Tyr-435 marks the ending of subsite +2 and may influence binding of the interacting substrate at the aglycone
binding sites. This study reports the effects of Tyr-435 using site-directed mutagenesis technique. Mutation of Tyr-435 to
Ala (mutant Y435A) enhanced both binding and catalytic efficiency of VhChiA, whereas substitution of Tyr-435 to Trp (mutant Y435W) lessened the ability of the enzyme to bind and hydrolyze chitin
substrates. The increased activity of Y435A can be explained by partial removal of a steric clash around subsite (+2), thereby
allowing a chitin chain to move beyond or to access the enzyme’s active site from the aglycone side more straightforwardly. |
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