Properties of extracellular neuraminidase produced by group A streptococcus

Abstract

Extracellular neuraminidase production by group A streptococci was examined in 92 strains. Fourteen of these strains produced appreciable amounts of enzyme; 12 of the neuraminidase-producing strains belonged to T types 1, 4, and 12. Production of the enzyme paralleled bacterial growth in culture and was maximal in medium containing 0.2% glucose. The enzyme produced by one of these strains was partially purified by ammonium sulfate fractionation and filtration on G-200 Sephadex. Its molecular weight was estimated at 90,000. Activity was optimal at pH 5.7 and in the presence of 0.01 to 0.03 M calcium and magnesium cations. The enzyme was stable at temperatures of 4 and 37C for at least 24 h but was inactivated within 10 min at temperatures of 50 and 65C. The enzyme hydrolyzed 40% of the sialic acid in bovine submaxillary mucin, but was inactive on sialyllactose, porcine submaxillary mucin, oligosaccharides derived from porcine mucin, or human orosomucoid. The K(m) value for this enzyme with bovine submaxillary mucin as substrate was in the order of 3.6x10-4M.