Title : Fluorescence investigation of yeast cytochrome c peroxidase oxidation by H2O2 and enzyme activities of the oxidized enzyme.

Pub. Date : 1994 Jan 11

PMID : 8286338






13 Functional Relationships(s)
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1 Fluorescence investigation of yeast cytochrome c peroxidase oxidation by H2O2 and enzyme activities of the oxidized enzyme. Hydrogen Peroxide cytochrome-c peroxidase Saccharomyces cerevisiae S288C
2 The role of tryptophan residues as endogenous electron donors in cytochrome c peroxidase (CCP) was examined by protein steady-state fluorescence. Tryptophan cytochrome-c peroxidase Saccharomyces cerevisiae S288C
3 The role of tryptophan residues as endogenous electron donors in cytochrome c peroxidase (CCP) was examined by protein steady-state fluorescence. Tryptophan cytochrome-c peroxidase Saccharomyces cerevisiae S288C
4 Compound I and more highly oxidized forms of CCP were formed by adding 1, 3, and 10 equiv of H2O2 to 5 microM protein at pH 7.0 in the absence of exogenous reducing substrates. Hydrogen Peroxide cytochrome-c peroxidase Saccharomyces cerevisiae S288C
5 Addition of native CCP to 8 M urea at pH 1.5 relieved heme quenching, and compound I exhibited 90 +/- 4% fluorescence relative to unoxidized CCP, consistent with the loss of 0.7 +/- 0.2 tryptophan and the assignment of the primary radical site to Trp191. Urea cytochrome-c peroxidase Saccharomyces cerevisiae S288C
6 Addition of native CCP to 8 M urea at pH 1.5 relieved heme quenching, and compound I exhibited 90 +/- 4% fluorescence relative to unoxidized CCP, consistent with the loss of 0.7 +/- 0.2 tryptophan and the assignment of the primary radical site to Trp191. Heme cytochrome-c peroxidase Saccharomyces cerevisiae S288C
7 Addition of native CCP to 8 M urea at pH 1.5 relieved heme quenching, and compound I exhibited 90 +/- 4% fluorescence relative to unoxidized CCP, consistent with the loss of 0.7 +/- 0.2 tryptophan and the assignment of the primary radical site to Trp191. Tryptophan cytochrome-c peroxidase Saccharomyces cerevisiae S288C
8 CCP oxidized with 10-fold excess H2O2 exhibited 65 +/- 1% relative fluorescence, indicating loss of 2.4 +/- 0.1 tryptophans. Hydrogen Peroxide cytochrome-c peroxidase Saccharomyces cerevisiae S288C
9 CCP oxidized with 10-fold excess H2O2 exhibited 65 +/- 1% relative fluorescence, indicating loss of 2.4 +/- 0.1 tryptophans. Tryptophan cytochrome-c peroxidase Saccharomyces cerevisiae S288C
10 Compound I and the higher oxidized forms of CCP spontaneously decayed to ferric CCP species over approximately 24 h with the loss of approximately 0.5 additional tryptophan in each case. Tryptophan cytochrome-c peroxidase Saccharomyces cerevisiae S288C
11 The fluorescence decrease with time paralleled the decrease in activity of H2O2-oxidized CCP using both ferrocytochrome c and ferrocyanide as substrates, indicating that tryptophan and activity loss occurred on similar time scales. Hydrogen Peroxide cytochrome-c peroxidase Saccharomyces cerevisiae S288C
12 The fluorescence decrease with time paralleled the decrease in activity of H2O2-oxidized CCP using both ferrocytochrome c and ferrocyanide as substrates, indicating that tryptophan and activity loss occurred on similar time scales. hexacyanoferrate II cytochrome-c peroxidase Saccharomyces cerevisiae S288C
13 The fluorescence decrease with time paralleled the decrease in activity of H2O2-oxidized CCP using both ferrocytochrome c and ferrocyanide as substrates, indicating that tryptophan and activity loss occurred on similar time scales. Tryptophan cytochrome-c peroxidase Saccharomyces cerevisiae S288C