Dissertations and Theses @ UNI
Availability
Open Access Thesis
Keywords
Plant enzymes.; Soybean;
Abstract
Azide ion is a mechanism-based inactivator of a number of peroxidases. However, there are often variations in the manner in which inactivation occurs. Soybean Peroxidase (SBP) is found in the plant's seed coat. Unlike many other peroxidases, a single enzyme rather than several isozymes are produced thus making more simple the purification and characterization of the enzyme. In this research it was shown that, as with other peroxidases, SBP is inactivated by azide during turnover. During azide oxidation SBP forms a ferrous-NO intermediate. In this respect, SBP is similar to the lignin peroxidases from Phanerochaete chrysosporium which also form ferrous-NO complexes as reaction intermediates. In contrast, horseradish peroxidase does not form a stable ferrous-NO complex. Of interest is the observation that, as long as a peroxidase remains in the ferrous-NO form it is resistant to inactivation. The SBP ferrous-NO complex is less stable than the ferrous-NO complex formed by lignin peroxidases.
Kinetic analysis revealed that inactivation was time and concentration dependent. The dissociation constant (K1) for SBP and azide was shown to be 1.05 mM. The pseudo-first order rate constant for inactivation (Kinact) was 0.06 sec-1 and t1/2 for inactivation was 12.2 sec. Azide did not inactivate SBP in the absence of hydrogen peroxide, a required oxidizing cosubstrate. Inactivation was irreversible and the heme moiety was destroyed during turnover.
Year of Submission
1998
Degree Name
Master of Science
Department
Department of Chemistry and Biochemistry
Department
Department of Chemistry
Date Original
1998
Object Description
1 PDF file (66 pages)
Copyright
©1998 Mohamed Yehia Zakaria Aboul Eish
Language
en
File Format
application/pdf
Recommended Citation
Aboul Eish, Mohamed Yehia Zakaria, "Inactivation of Soybean Peroxidase During Sodium Azide Oxidation: A Comparative Study" (1998). Dissertations and Theses @ UNI. 1588.
https://scholarworks.uni.edu/etd/1588
Comments
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