Agricultural Microbiology Research Department, Soils, Water and Environment Institute, Agricultural Research Center, Giza, Egypt
Abstract
Amylases of microbial origin are the basis for many commercial applications of hydrolytic enzymes. Large quantities of these enzymes are used in textile industry for the desizing of fabrics, in the paper industry for the preparation of starch slurries for coating paper, and in the food industry for the preparation of syrups for sweetening agents (Pazur, 1965). These enzymes are usually extracellular, inducible and remain in the culture fluids after removal of the microorganisms (Alexander, 1977 & 1981). But the ability of microorganisms to form amylolytic enzymes depends on the type of starch. The optimum pH and the isoelectric points of these enzymes are also quite similar. The amino acid composition and its values for some of the microbial cc-amylase are recorded in Table 1. Significant differences are apparent in amino acid composition among the amylases from the different organisms. Investigations thus far reported on the determination of N-terminal and carboxyl-terminal amino acids indicate that a bacterial amylase is composed of two polypeptide chains presumably held together by disulfide bonds, whereas a fungal amylase may consist of a branched structure (Pazur, 1965 and Kulp, 1975).
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