Related Experiment Videos
A conserved cysteine in molybdenum oxotransferases
1Department of Biochemistry and Molecular Biology, University of South Florida, College of Medicine, Tampa.
The Journal of Biological Chemistry
|December 5, 1990
Summary
Rat liver sulfite oxidase has 3 cysteine residues. Two are conserved with chicken sulfite oxidase, and one may bind Mo-pterin in related enzymes.
Area of Science:
- Biochemistry
- Enzymology
- Molecular Biology
Background:
- Sulfite oxidase is a crucial enzyme in sulfur metabolism.
- Understanding enzyme structure, particularly cysteine residues, is key to function.
- Comparative analysis across species can reveal conserved functional elements.
Purpose of the Study:
- To determine the amino acid sequences of peptides from rat hepatic sulfite oxidase.
- To identify and characterize cysteine residues in the rat enzyme.
- To compare these findings with chicken sulfite oxidase and other related enzymes.
Main Methods:
- Amino acid analysis and Edman degradation of purified rat hepatic sulfite oxidase.
- Thiol modification studies using 4,4'-dithiodipyridine.
- Sequence comparison with chicken sulfite oxidase and assimilatory nitrate reductases.
Main Results:
- Rat liver sulfite oxidase contains 3 cysteine residues.
- Two cysteine residues (Cys186 and Cys430) are conserved between rat and chicken enzymes.
- A single cysteine residue (Cys186) is conserved across sulfite oxidases and nitrate reductases.
Conclusions:
- Cysteine residues in rat hepatic sulfite oxidase are located within the molybdenum-binding domain.
- Conserved cysteines suggest important structural or functional roles.
- The conserved Cys186 may be involved in binding the molybdenum cofactor (Mo-pterin).