| Popis: |
Alpha-amylase from culture filtrates of Streptomyces rimosus, oxytetracycline producing strain, was purified to homogeneity. It hydrolyzed soluble starch and amylopectin, having kinetic coefficient of kcat/Km of 231 and 139 ml mg-1sec-1, respectively. Optimal conditions for the activity were pH 5-6 and 47oC. The enzyme was shown to be an acidic monomer of relative molecular mass of 43 000, stable at pH 5-9 and up to 40oC. The presence of Ca2+ ions increased its stability. Isolated alpha-amylase was inhibited by thiol reagents and to some extent by chlating agents and anionic detergent, whereas activation by metal and chloride ions was not observed. Calcium and cobalt cations protected the nzyme from reagents which block SH-groups. Amino acid composition revealed the presence of three cysteins per molecule of enzyme, at least one of which participates in it activity. Determined amino acid sequence at the NH2-terminus, when aligned with the known sequences of alpha-amylase from other Streptomyces species showed 57-60 % homology. Immune serum specific for alpha-amylase from S. rimosus was prepared and used for determination of its relation to other alpha-amylases. |
