Purification and characterization of the hyper-glycosylated extracellular α-glucosidase from Schizosaccharomyces pombe

alpha-Glucosidase secreted from Schizosaccharomyces pombe cell has been purified as a homogeneous protein from culture supernatant. The alpha-glucosidase is hyper-glycosylated form, which included 88% of sugar components, and the relative molecular mass is calculated in 1120 kDa. Heat stability and proteolysis susceptibility of the alpha-glucosidase is descended by enzymatical deglycosylation. By MALDI-TOF NIS analysis, seven Asn residues (Asn185, Asn221, Asn496, Asn499, Asn572, Asn777 and Asn787; numbering from N-terminal of matured form) out of 27 potential N-glycosylation sites of the enzyme are presumed to be modified. The native form of S. pombe a-glucosidase have three subsites in the catalytic site and so prefer alpha-1,4-glucosidic linkage in short substrates, such as maltose and maltotriose, to longer substrate. The enzyme also acts on alpha- 1,2, alpha- 1,3, and alpha-1,6-glucosidic linkage. (c) 2005 Elsevier Inc. All rights reserved.