Purification and characterization of a thermostable α-amylase produced by the fungus Paecilomyces variotii.

Autor: Michelin M; Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Monte Alegre, Ribeirão Preto-SP, 14040-901, Brazil., Silva TM, Benassi VM, Peixoto-Nogueira SC, Moraes LA, Leão JM, Jorge JA, Terenzi HF, Polizeli Mde L
Jazyk: angličtina
Zdroj: Carbohydrate research [Carbohydr Res] 2010 Nov 02; Vol. 345 (16), pp. 2348-53. Date of Electronic Publication: 2010 Aug 25.
DOI: 10.1016/j.carres.2010.08.013
Abstrakt: An α-amylase produced by Paecilomyces variotii was purified by DEAE-cellulose ion exchange chromatography, followed by Sephadex G-100 gel filtration and electroelution. The α-amylase showed a molecular mass of 75 kDa (SDS-PAGE) and pI value of 4.5. Temperature and pH optima were 60°C and 4.0, respectively. The enzyme was stable for 1 h at 55°C, showing a t₅₀ of 53 min at 60°C. Starch protected the enzyme against thermal inactivation. The α-amylase was more stable in alkaline pH. It was activated mainly by calcium and cobalt, and it presented as a glycoprotein with 23% carbohydrate content. The enzyme preferentially hydrolyzed starch and, to a lower extent, amylose and amylopectin. The K(m) of α-amylase on Reagen® and Sigma® starches were 4.3 and 6.2 mg/mL, respectively. The products of starch hydrolysis analyzed by TLC were oligosaccharides such as maltose and maltotriose. The partial amino acid sequence of the enzyme presented similarity to α-amylases from Bacillus sp. These results confirmed that the studied enzyme was an α-amylase ((1→4)-α-glucan glucanohydrolase).
(Copyright © 2010 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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