Production and application of tannin acyl hydrolase: state of the art

Colorimetric assay method for determination of the tannin acyl hydrolase (EC 3.1.1.20) activity

A new colorimetric method of tannase (tannin acyl hydrolase, EC 3.1.1.20) assay has been developed using its specific substrate tannic acid. It is based on the changes in optical density of substrate tannic acid after enzymatic reaction at 530 nm. The residual tannic acid was measured by a modified BSA precipitation method. This assay is very simple, reproducible, and very convenient, and with it tannase activity can be measured in relation to the growth of the organism.

A new tannase substrate for spectrophotometric assay

A new tannase substrate, protocatechuic acid p-nitrophenyl ester, 5, was synthesized using modern synthetic methods. The synthesis was designed to be performed by non-specialized chemists. It only involves four steps, three of which are protection-deprotection, and uses standard methods of separation and purification, such as recrystallization and column chromatography over silica. Under tannase action, protocatechuic acid p-nitrophenyl ester, 5, releases p-nitrophenol, which is easily measured spectrophotometrically either at 350 nm for pH values<6 or at 400 nm for pH values of 6-7 (yellow). The pH-response and the catalytic parameters of a crude Penicillium sp. tannase preparation were determined using 5 as substrate, thus showing the usefulness of this substrate in determining tannase activity.

A spectrophotometric method for assay of tannase using rhodanine

A method for assay of microbial tannase (tannin acyl hydrolase) based on the formation of chromogen between gallic acid and rhodanine is reported. Unlike the previous protocols, this method is sensitive up to gallic acid concentration of 5 nmol and has a precision of 1.7% (relative standard deviation). The assay is complete in a short time, very convenient, and reproducible.

Purification and characterization of gallic acid decarboxylase from pantoea agglomerans T71

Oxygen-sensitive gallic acid decarboxylase from Pantoea (formerly Enterobacter) agglomerans T71 was purified from a cell extract after stabilization by reducing agents. This enzyme has a molecular mass of approximately 320 kDa and consists of six identical subunits. It is highly specific for gallic acid. Gallic acid decarboxylase is unique among similar decarboxylases in that it requires iron as a cofactor, as shown by plasma emission spectroscopy (which revealed an iron content of 0.8 mol per mol of enzyme subunit), spectrophotometric analysis (absorption shoulders at 398 and 472 nm), and inhibition of the enzyme activity by 2,2'-bipyridyl, o-phenanthroline, and EDTA. Another interesting feature of this strain is the fact that it contains a tannase, which is used together with the gallic acid decarboxylase in a two-enzyme resting cell bioconversion to synthesize valuable pyrogallol from readily available tannic acid.