Studies on the mechanism of hyaluronate lyase action

Hyaluronate lyase from streptococci group A was purified by chromatography on DEAE-Sephadex A-50 and on Biogel P-150, thereby enriching it about 1,000-fold and separating it into two enzyme fractions with the same amino acid composition. The photooxidation of hyaluronate lyase in the presence of methylene blue results in rapid inactivation of the enzyme. The histidine content of the enzyme is decreased considerably, but also the content of methionine, tyrosine, and lysine is lowered. The enzyme is inhibited, but incompletely so, by N-tosyl-L-phenyl-alanine-chloromethyl ketone (TPCK) and N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK). Hyaluronic acid methyl ester, prepared form hyaluronic acid and diazomethane, is not split by hyaluronate lyase (EC 4.2.2.1.). Hyaluronic acid methyl ester is not a competitive inhibitor of hyaluronate lyase. For the mechanism of the enzymatic elimination reaction a proton transfer between histidine of the enzyme and the carboxylate group of hyaluronate is proposed.