Biochemical and Structural Characterization of a Novel Bacterial Tannase From in Ruminant Gastrointestinal Tract.

Tannases are a family of esterases that catalyze the hydrolysis of ester and depside bonds present in hydrolyzable tannins to release gallic acid. Here, a novel tannase from (TanA) was characterized. The recombinant TanA exhibited maximal activity at pH 7.0 and 50°C, and it maintained more than 70% relative activity from 30°C to 55°C. The activity of TanA was enhanced by Mg and Ca, and was dramatically reduced by Cu and Mn. TanA is capable of degrading esters of phenolic acids with long-chain alcohols, such as lauryl gallate as well as tannic acid. The m value and catalytic efficiency ( /m) of TanA toward five substrates showed that tannic acid (TA) was the favorite substrate. Homology modeling and structural analysis indicated that TanA contains an insertion loop (residues 341-450). Based on the moleculer docking and molecular dynamics (MD) simulation, this loop was observed as a flap-like lid to interact with bulk substrates such as tannic acid. TanA is a novel bacterial tannase, and the characteristics of this enzyme make it potentially interesting for industrial use.