ABSTRACT
The substrate specificity of selected enzymes classified under Carbohydrate Esterase family 4 (CE4) has been examined. Chitin deacetylase from Mucor rouxii and both a native and a truncated form of acetyl xylan esterase from Streptomyces lividans were found to be active on both xylan and several soluble chitinous substrates. Furthermore, the activities of all enzymes examined were significantly increased in the presence of Co(2+) when chitinous substrates were employed. However, the presence of this metal ion did not result in enhancing the activities of the enzymes when xylan was used as substrate. An acetyl xylan esterase from Bacillus pumilus, classified under Carbohydrate Esterase family 7, was found to be inactive towards all chitinous substrates tested. Finally, all enzymes examined were inactive towards cell wall peptidoglycan.
Subject(s)
Carbohydrate Metabolism , Carboxylic Ester Hydrolases/metabolism , Acetylesterase/genetics , Acetylesterase/metabolism , Amidohydrolases/genetics , Amidohydrolases/metabolism , Amino Acid Sequence , Bacillus/enzymology , Bacillus/genetics , Carbohydrate Conformation , Carbohydrates/chemistry , Carboxylic Ester Hydrolases/genetics , Carboxylic Ester Hydrolases/isolation & purification , Cloning, Molecular , Cobalt/pharmacology , Conserved Sequence/genetics , Enzyme Activation/drug effects , Gene Expression Regulation, Bacterial , Gene Expression Regulation, Enzymologic , Molecular Sequence Data , Mucor/enzymology , Mucor/genetics , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Streptomyces/enzymology , Streptomyces/genetics , Substrate SpecificityABSTRACT
Chitin deacetylase (Cda2p) (EC 3.5.1.41) from Saccharomyces cerevisiae has been purified from vegetative cells grown in galactose and further characterized. The enzyme is a glycoprotein with an apparent molecular mass of approximately 43 kDa and a carbohydrate content of approximately 18% by weight. With glycol chitin as substrate, the optimum temperature for enzyme activity is 50 degrees C and the pH optimum is 8.0. The enzyme requires at least two N-acetyl-D-glucosamine residues (chitobiose) for catalysis and is partially inhibited by acetate. Deglycosylation of the enzyme causes total loss of enzyme activity, which can be restored by the addition of COCl(2).
