Immobilized enzymes: Pectin esterase covalently coupled to dorous glass particles
作者:
M. K. Weibel,
Roberto Barrios,
R. Delotto,
A. E. Humphrey,
期刊:
Biotechnology and Bioengineering
(WILEY Available online 1975)
卷期:
Volume 17,
issue 1
页码: 85-98
ISSN:0006-3592
年代: 1975
DOI:10.1002/bit.260170107
出版商: Wiley Subscription Services, Inc., A Wiley Company
数据来源: WILEY
摘要:
AbstractPectin esterase (E.C. 3.1.1.11) was covalently immobilized to porous glass particles by reaction of the native protein with pendant, benzoyl azide groups of the carrier. Enzyme loading on the carrier was 0.5 unit per ml as measured by pH stat, assay. Decreasing the size of the immobilized enzyme particles by grinding produced a 12‐fold increase in activity suggesting severe internal mass transport restrictions on turnover kinetics, Gross fractionation of the citrus pectin substrate into high and low molecular weight categories and their subsequent use in kinetic characterization shows no effect of molecular weight upon the kinetic behavior of the native enzyme. In contrast the immobilized enzyme displayed a 5‐fold increase in the apparent.Kmfor the high molecular weight fraction relative to that of the low molecular weight fraction. A striking difference exists in the low pH profile of immobilized pectin esterase relative to the native enzyme. Carrier matrix interactions with the polyelectrolyte substrate are invoked to explain this difference. The thermal stability of the immobilized enzyme is relatively low and displays a half‐life of approximately 2 weeks at
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