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Protein-bound 3,4-dihydroxyphenylalanine is a major reductant formed during hydroxyl radical damage to proteins.
- Source :
-
Biochemistry [Biochemistry] 1993 May 11; Vol. 32 (18), pp. 4780-6. - Publication Year :
- 1993
-
Abstract
- Proteins and aromatic amino acids previously exposed to hydroxyl radicals reduced cytochrome c, free iron, and copper ions. A major product of hydroxyl radical addition to tyrosine is 3,4-dihydroxyphenylalanine (DOPA), which has these reducing properties. The reduction of nitro blue tetrazolium by radical-damaged protein was consistent with the generation of quinones in the protein. By acid hydrolysis followed by high-performance C18 reversed-phase liquid chromatography we have shown that hydroxyl radical-damaged proteins contain significant amounts of protein-bound DOPA (PB-DOPA). The authenticity of the DOPA measured was confirmed by gas chromatography-mass spectrometry. PB-DOPA was also generated enzymatically using mushroom tyrosinase, which catalyzes the hydroxylation of tyrosine residues. By comparing the levels of DOPA in radical-damaged or enzyme-treated protein with that of cytochrome c reduction, we show that PB-DOPA is a major source of the observed reducing activity. PB-DOPA may have a role in the replenishment of reduced transition metal ions involved in free radical generating systems in vivo.
- Subjects :
- Catechols chemistry
Copper pharmacology
Cytochrome c Group chemistry
Free Radicals
Insulin chemistry
Insulin radiation effects
Models, Chemical
Monophenol Monooxygenase pharmacology
Oxidation-Reduction
Proteins drug effects
Proteins radiation effects
Quinones chemistry
Serum Albumin, Bovine chemistry
Serum Albumin, Bovine drug effects
Serum Albumin, Bovine radiation effects
Tyrosine drug effects
Tyrosine radiation effects
Dihydroxyphenylalanine chemistry
Proteins chemistry
Tyrosine analogs & derivatives
Subjects
Details
- Language :
- English
- ISSN :
- 0006-2960
- Volume :
- 32
- Issue :
- 18
- Database :
- MEDLINE
- Journal :
- Biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 8387814
- Full Text :
- https://doi.org/10.1021/bi00069a012