Cell bound and extracellular glucose oxidases from Aspergillus niger BTL: Evidence for a secondary glycosylation mechanism

Hatzinikolaou, DG; Mamma, D; Christakopoulos, P; Kekos, D

dc.contributor.author	Hatzinikolaou, DG	en
dc.contributor.author	Mamma, D	en
dc.contributor.author	Christakopoulos, P	en
dc.contributor.author	Kekos, D	en
dc.date.accessioned	2014-03-01T01:26:00Z
dc.date.available	2014-03-01T01:26:00Z
dc.date.issued	2007	en
dc.identifier.issn	0273-2289	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/17868
dc.subject	Aspergillus niger BTL	en
dc.subject	Glucose oxidase isoform	en
dc.subject	GOX II	en
dc.subject	GOXI	en
dc.subject.classification	Biochemistry & Molecular Biology	en
dc.subject.classification	Biotechnology & Applied Microbiology	en
dc.subject.other	Cell culture	en
dc.subject.other	Dimers	en
dc.subject.other	Glucose oxidase	en
dc.subject.other	Glycosylation	en
dc.subject.other	Molecular mass	en
dc.subject.other	pH effects	en
dc.subject.other	Aspergillus niger	en
dc.subject.other	Glucose oxidase isoform	en
dc.subject.other	Fungi	en
dc.subject.other	carbohydrate	en
dc.subject.other	glucose oxidase	en
dc.subject.other	glucose	en
dc.subject.other	isoprotein	en
dc.subject.other	article	en
dc.subject.other	Aspergillus niger	en
dc.subject.other	controlled study	en
dc.subject.other	electrophoresis	en
dc.subject.other	enzyme kinetics	en
dc.subject.other	enzyme purification	en
dc.subject.other	enzyme specificity	en
dc.subject.other	enzyme synthesis	en
dc.subject.other	glycosylation	en
dc.subject.other	nonhuman	en
dc.subject.other	pH measurement	en
dc.subject.other	thermostability	en
dc.subject.other	biotechnology	en
dc.subject.other	chemistry	en
dc.subject.other	dimerization	en
dc.subject.other	enzymology	en
dc.subject.other	isoelectric point	en
dc.subject.other	kinetics	en
dc.subject.other	metabolism	en
dc.subject.other	methodology	en
dc.subject.other	molecular weight	en
dc.subject.other	mycelium	en
dc.subject.other	pH	en
dc.subject.other	temperature	en
dc.subject.other	Aspergillus niger	en
dc.subject.other	Aspergillus niger	en
dc.subject.other	Biotechnology	en
dc.subject.other	Carbohydrates	en
dc.subject.other	Dimerization	en
dc.subject.other	Glucose	en
dc.subject.other	Glucose Oxidase	en
dc.subject.other	Glycosylation	en
dc.subject.other	Hydrogen-Ion Concentration	en
dc.subject.other	Isoelectric Point	en
dc.subject.other	Kinetics	en
dc.subject.other	Molecular Weight	en
dc.subject.other	Mycelium	en
dc.subject.other	Protein Isoforms	en
dc.subject.other	Substrate Specificity	en
dc.subject.other	Temperature	en
dc.title	Cell bound and extracellular glucose oxidases from Aspergillus niger BTL: Evidence for a secondary glycosylation mechanism	en
heal.type	journalArticle	en
heal.identifier.primary	10.1007/s12010-007-0006-7	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s12010-007-0006-7	en
heal.language	English	en
heal.publicationDate	2007	en
heal.abstract	Two glucose oxidase (GOX) isoforms where purified to electrophoretic homogeneity from the mycelium extract (GOX(I)) and the extracellular medium (GOX(II)) of Aspergillus niger BTL cultures. Both enzymes were found to be homodimers with nonreduced molecular masses of 148 and 159 kDa and pI values of 3.7 and 3.6 for GOX(I) and GOX(II), respectively. The substrate specificity and the kinetic characteristics of the two GOX forms, as expressed through their apparent Km values on glucose, as well as pH and T activity optima, were almost identical. The only structural difference between the two enzymes was in their degrees of glycosylation, which were determined equal to 14.1 and 20.8% (w/w) of their molecular masses for GOX(I) and GOX(II), respectively. The above difference in the carbohydrate content between the two enzymes seems to influence their pH and thermal stabilities. GOX(II) proved to be more stable than GOX(I) at pH values 2.5, 3.0, 8.0, and 9.0. Half-lives of GOX(I) at pH 3.0 and 8.0 were 8.9 and 17.5 h, respectively, whereas the corresponding values for GOX(II) were 13.5 and 28.1 h. As far as the thermal stability is concerned, GOX(II) was also more thermostable than GOX(I) as judged by the deactivation constants determined at various temperatures. More specifically, the half-lives of GOX(I) and GOX(II), at 45 C, were 12 and 49 h, respectively. These results suggest A. niger BTL probably possesses a secondary glycosylation mechanism that increases the stability of the excreted GOX.	en
heal.publisher	HUMANA PRESS INC	en
heal.journalName	Applied Biochemistry and Biotechnology	en
dc.identifier.doi	10.1007/s12010-007-0006-7	en
dc.identifier.isi	ISI:000250069800003	en
dc.identifier.volume	142	en
dc.identifier.issue	1	en
dc.identifier.spage	29	en
dc.identifier.epage	43	en