科研之友
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摘要
Aspergillus awamori BTMFW032, isolated from sea water, produced tannase as an extracellular enzyme under submerged culture conditions. Enzymes with a specific activity of 2,761.89 IU/mg protein, a final yield of 0.51%, and a purification fold of 6.32 were obtained after purification through to homogeneity, by ultrafiltration and gel filtration. SDS-PAGE analyses, under nonreducing and reducing conditions, yielded a single band of 230 kDa and 37.8 kDa, respectively, indicating the presence of six identical monomers. A pl of 4.4 and a carbohydrate content of 8.02% were observed in the enzyme. The optimal temperature was found to be 30 degrees C, although the enzyme was active in the range of 5-80 degrees C. Two pH optima, pH 2 and pH 8, were recorded, although the enzyme was instable at a pH of 8, but stable at a pH of 2.0 for 24 h. Methylgallate recorded maximal affinity, and K(m) and V(max) were recorded at 1.9x 10(-3) M and 8301 mu mol/min, respectively. The impacts of a number of metal salts, solvents, surfactants, and other typical enzyme inhibitors on tannase activity were determined in order to establish the novel characteristics of the enzyme. The gene encoding tannase, isolated from A. awamori, was found to be 1.232 kb, and nucleic acid sequence analysis revealed an open reading frame consisting of 1,122 bp (374 amino acids) of one stretch in the -1 strand. In silica analyses of gene sequences, and a comparison with reported sequences of other species of Aspergillus, indicate that the acidophilic tannase from marine A. awamori differs from that of other reported species.
- 出版日期2010-10
