, Volume 77, Issue 1, pp 77-89
Date: 05 Sep 2007

Purification and characterization of two cold-adapted extracellular tannin acyl hydrolases from an Antarctic strain Verticillium sp. P9

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Abstract

Two extracellular tannin acyl hydrolases (TAH I and TAH II) produced by an Antarctic filamentous fungus Verticillium sp. P9 were purified to homogeneity (7.9- and 10.5-fold with a yield of 1.6 and 0.9%, respectively) and characterized. TAH I and TAH II are multimeric (each consisting of approximately 40 and 46 kDa sub-units) glycoproteins containing 11 and 26% carbohydrates, respectively, and their molecular mass is approximately 155 kDa. TAH I and TAH II are optimally active at pH of 5.5 and 25 and 20°C, respectively. Both the enzymes were activated by Mg2+and Br ions and 0.5–2.0 M urea and inhibited by other metal ions (Zn2+, Cu2+, K+, Cd2+, Ag+, Fe3+, Mn2+, Co2+, Hg2+, Pb2+ and Sn2+), \({\text{CO}}_{\text{3}}^{{\text{2}} - }\) anions, Tween 20, Tween 60, Tween 80, Triton X-100, sodium dodecyl sulphate, β-mercaptoethanol, α-glutathione and 4-chloromercuribenzoate. Both tannases more efficiently hydrolyzed tannic acid than methyl gallate. E a of these reactions and temperature dependence (at 0–30°C) of k cat, k cat/K m, ΔG*, ΔH* and ΔS* for both the enzymes and substrates were determined. The k cat and k cat/K m values (for both the substrates) were considerably higher for the combined preparation of TAH I and TAH II.