THE CARBOHYDRATE MOIETY OF THE ACID CARBOXYPEPTIDASE FROM ASPERGILLUS-SAITOI

Acid carboxypeptidase from Aspergillus saitoi is a glycoprotein that c ontains both N- and O-linked sugar chains. The N-glycanase released hi gh-mannose type oligosaccharides that were separated into eight compon ents on HPLC. One, which had a unique structure of Man11GlcNAc2, was c haracterized. Mild alkali treatment of the carboxypeptidase, under con ditions that effect beta-elimination, yielded D-mannose. Deglycosylati on of the carboxypeptidase with endo-beta-N-acetylglucosaminidase and alpha-mannosidase effected the reduction of the molecular mass from 72 kDa to 60 kDa. Partial changes of CD spectra of the native and the de glycosylated enzymes indicate that some conformational changes on the peptide of the enzyme occurred after deglycosylation. Other enzymatic properties, such as catalytic activity, pH, and thermal stability and resistivity to protease digestion, did not appear to change. Tunicamyc in halted secretion of the carboxypeptidase extracellularly.