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The sulfinic acid switch in proteins
Claus Jacob1, Andrea L Holme, Fiona H Fry
1School of Biological and Chemical Sciences, University of Exeter, Stocker Road, Exeter, United KingdomEX4 4QD. C.Jacob@ex.ac.uk
Organic & Biomolecular Chemistry
|July 16, 2004
Summary
Cysteine sulfinic acid formation in proteins is reversible. Newly discovered sulfiredoxin enzymes reduce these oxidized cysteine residues, revealing new redox signaling pathways.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Signaling
Background:
- Cysteine residues in proteins play key roles in biocatalysis, redox sensing, and cell signaling.
- Cysteine sulfinic acid formation was traditionally considered irreversible oxidative damage.
- This 'overoxidation' could lead to protein inactivation, particularly under oxidative stress.
Purpose of the Study:
- To investigate the reversibility of cysteine sulfinic acid formation in proteins.
- To identify mechanisms and enzymes involved in reducing cysteine sulfinic acids in vivo.
- To explore the implications of this reversibility for cellular redox processes.
Main Methods:
- Studies on redox behavior of cysteine residues in peptides and proteins.
- Isolation of sulfinic acid reductase activity from yeast.
- Identification of a human gene encoding a homologous enzyme.
Main Results:
- Sulfinic acids, previously thought irreversible, can be reduced back to thiols in vivo.
- An enzyme, sulfiredoxin, with sulfinic acid reductase activity was isolated from yeast.
- A human gene homologous to yeast sulfiredoxin was identified.
Conclusions:
- The reversibility of cysteine sulfinic acid formation opens new avenues for understanding cellular redox cycles.
- This discovery has significant implications for cell signaling and protein regulation under oxidative stress.
- Cysteine-based redox processes are of broad interest to multiple scientific disciplines and medicine.