Chitin and Yeast Budding. PROPERTIES OF CHITIN SYNTHETASE FROM SACCHAROMYCES CARLSBERGENSIS
J. Biol. Chem., 246 (1):
160-166 (1971)Abstract
A particulate preparation from a spheroplast lysate of Saccharomyces carlsbergensis was found to catalyze the transfer of acetylglucosamine from UDP-acetylglucosamine to an endogenous acceptor. Uridine diphosphate is liberated in stoichiometric amounts. A divalent cation, Mg2+, Mn2+, or Co2+, is required for enzymatic activity. Acetylglucosamine stimulates the activity about 5-fold, with a Km of 4.7 mm, and can be partially replaced by high concentrations of glucose, mannose, cellobiose, and glycerol. The Km for UDP-acetyl-glucosamine is between 0.6 and 0.9 mm and the pH optimum is 6.2. Centrifugation in sucrose gradients indicates that the reaction product remains bound to the same particles which contain the activity. The product was characterized as chitin by its insolubility in alkali, the release of glucosamine on acid hydrolysis, and the liberation of diacetylchitobiose and acetylglucosamine following stepwise enzymatic hydrolysis. The enzyme is inhibited by monovalent and polyvalent anions, the latter being more effective. The antibiotic Polyoxin A is a very potent competitive inhibitor, with a Ki of 5 x 10-7 m. Polyoxin A affected neither growth of intact cells nor synthesis of chitin by naked spheroplasts. It is concluded that chitin synthetase is not located outside the cytoplasmic membrane.
Description
Chitin and Yeast Budding. PROPERTIES OF CHITIN SYNTHETASE FROM SACCHAROMYCES CARLSBERGENSIS -- Keller and Cabib 246 (1): 160 -- Journal of Biological Chemistry