Production and characterization of alpha-amylase from Rhizopus sp

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deSouza, E. L.
Hoffmann, EHE
Castilho, V. M.
deLima, V. A.
Bellini, M. Z.
Cruz, V. D.
Cruz, R.

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Inst Tecnologia Parana


A strain of Rhizopus sp. screened among more than 800 filamentous fungi showed great ability to produce a thermostable alpha-amylase by solid state fermentation. The best production was obtained with a bran moisture content of 40% when the enzyme activity reached 60 EU/g. of medium. During the purification procedures, a column of DEAE-Sephadex A-50 separated the enzyme in two fractions and the larger (85% of the total activity) showed optimum pH in a range from 4.0 to 5.6. Optimum temperature was found at 60-65 degrees C and in this range no loss of activity was observed after 60 min. of treatment in pH 5,0. Its K-m and V-m are, respectively, of 5.0 mg/ml of starch and 10,01 uMol of reducing sugar/min./mg. of protein. Its molecular weight was calculated in 64.000 by gel filtration in Sephadex G-200. The dextrinization power of the enzyme was observed preferentialy on substrates compound by chains with higher ramifications, that is: amylopectin > starch > amylose. Other aspects of the enzyme pattern action are also discussed.



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Arquivos de Biologia E Tecnologia. Curitiba-Paraná: Inst Tecnologia Parana, v. 39, n. 4, p. 831-839, 1996.