Extracellular neuraminidase of Streptomyces albus

Abstract

Extracellular neuraminidase activity (mucopolysaccharide N-acetylneuraminylhydrolase, EC.3.2.1.18) was detected in culture filtrates of Streptomyces albus MA-390, S. albus NCTC 7807, and S. albidoflaviis, but not S. albus ATCC 3004, S. roseochromogenes ATCC 13400, or S. venezuelae ATCC 10595. Neuraminidase of S. albus MA-390, purified 430-fold from crude culture filtrates, cleaved N-acetylneuraminyllactose and released thiobarbituric acid-reactive material from various glycoproteins. With excess substrate the reaction rate was proportional to enzyme concentration. The enzyme was not stimulated by divalent metal ions and was not inhibited by ethylenediaminetetraacetate. Streptomyces albus MA-390 neuraminidase was heat labile and activity was lost rapidly at temperatures of 40°C and above. With N-acetylneuraminyllactose as substrate optimal activity occurred at pH 6.0, but with fetal bovine serum the pH optimum was 3.5. The molecular weight of the enzyme was estimated by gel filtration to be in the range of 40 000 to 45 000.