Hydrolyzing Pathway, Substrate Specificity and Inhibition of Tannin Acyl Hydrolase of Asp. oryzae No. 7

Abstract

Tannin acyl hydrolase (EC 3.1.1.20) of Asp. oryzae No. 7 hydrolyzes tannic acid to glucose and gallic acid. The intermediate hydrolyzates are 1,2,3,4,6-pentagalloyl glucose, 2,3,4,6-tetragalloyl glucose and two kinds of monogalloyl glucose.The enzyme hydrolyzes ester compounds of gallic acid, but does not hydrolyze any other substrate analogues such as methyl-resorcyrate.The enzyme reaction is inhibited competitively by substrate analogues which have phenolic hydroxyls with the exception that 2,6-dihydroxy benzoic acid inhibits noncompetitively. Therefore the binding site of the enzyme may be able to react with any kind of phenolic hydroxyl, although the substrate forming a true ES-complex must be an ester compound of gallic acid.