Purification and properties of an extracellular glucoamylase from a diastatic strain of Saccharomyces cerevisiae.
The extracellular glucoamylase from certain strains of Saccharomyces cerevisiae can be purified from culture medium by a simple chromatographic procedure. The native enzyme is heavily glycosylated and has an Mr of about 250,000, but gel filtration indicates the existence of oligomers of larger size. Dissociation yields a form of Mr about 70,000. The glucoamylase is rich in serine and threonine and in aspartic acid plus asparagine, and has a pI of 4.62 and a pH optimum of 4.5-6.5. The thermostability and resistance to denaturants of the yeast enzyme is compared with those of two other fungal glucoamylases. Kinetic data for the yeast enzyme and a variety of substrates is presented; the enzyme is particularly ineffective in cleaving alpha-(1----6)-glycosidic bonds.
D000596:Amino Acids / Q000032:analysis; D001236:Aspergillus oryzae / Q000201:enzymology; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005087:Glucan 1,4-alpha-Glucosidase / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D005959:Glucosidases / Q000302:isolation & purification*; D006207:Half-Life; D007525:Isoelectric Focusing; D007700:Kinetics; D012233:Rhizopus / Q000201:enzymology; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity
D000596:Amino Acids; D005959:Glucosidases; D005087:Glucan 1,4-alpha-Glucosidase