Ascorbate peroxidase activity of cytochrome c.
The peroxidase-type reactivity of cytochrome c is proposed to play a role in free radical production and/or apoptosis. This study describes cytochrome c catalysis of peroxide consumption by ascorbate. Under conditions where the sixth coordination position at the cytochrome c heme iron becomes more accessible for exogenous ligands (by carboxymethylation, cardiolipin addition or by partial denaturation with guanidinium hydrochloride) this peroxidase activity is enhanced. A reaction intermediate is detected by stopped-flow UV-vis spectroscopy upon reaction of guanidine-treated cytochrome c with peroxide, which resembles the spectrum of globin Compound II species and is thus proposed to be a ferryl species. The ability of physiological levels of ascorbate (10-60 µM) to interact with this species may have implications for mechanisms of cell signalling or damage that are based on cytochrome c/peroxide interactions.
Department of Chemistry and Chemical Engineering, 'Babes-Bolyai' University, Cluj-Napoca RO-400028, Romania. cristina_bischin@yahoo.com
Cristina
C
Bischin
Florina
F
Deac
Radu
R
Silaghi-Dumitrescu
Jonathan A R
JA
Worrall
Badri S
BS
Rajagopal
Grigore
G
Damian
Chris E
CE
Cooper
D000818:Animals; D017209:Apoptosis; D001205:Ascorbic Acid / Q000378:metabolism; D002308:Cardiolipins / Q000378:metabolism; D002417:Cattle; D003578:Cytochrome-c Peroxidase / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism*; D005609:Free Radicals / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry / Q000378:metabolism; D006418:Heme / Q000737:chemistry; D006736:Horses; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D008745:Methylation; D008929:Mitochondria, Heart / Q000201:enzymology*; D015398:Signal Transduction; D013057:Spectrum Analysis; D015003:Yeasts
D002308:Cardiolipins; D005609:Free Radicals; C066317:ferryl iron; D006418:Heme; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D007501:Iron; D003578:Cytochrome-c Peroxidase; D019791:Guanidine; D001205:Ascorbic Acid