Studies on Tannin Acyl Hydrolase of Microorganisms

Abstract

A new method determining the activity of tannin acyl hydrolase (tannase) was made. This method was based on the change in optical density of substrate tannic acid at 310 mμ. In this method, the error of measurement was about 1~3%, and many samples could be tested at one time because of its simplicity. The procedure was as follows; To four parts of substrate (0.350 w/v% of tannic acid dissolved in 0.05m citrate buffer, pH 5.5), one part of the enzyme solution was added. After t minutes reaction at 30°C, 0.1 part of the mixture was added to ten parts of 90% ethanol. The optical density of the ethanol solution at 310 mμ was measured. Tannase activity (unit/ml) was given by following equation.u=114×Et1−Et2t2−t1 Where Et1 and Et2 mean the optical density of the ethanol solution at 310 mμ prepared after t1 and t2 minutes reaction, and one unit of the enzyme means the amount of the enzyme which is able to hydrolyze one μ mole of the ester bond in tannic acid in one minute. The substrate tannic acid used in this determining method was purified. It was composed of one mole of glucose and nine moles of gallic acid, and eight moles of which formed four moles of m-digallic acid.