2CEP

ROLE OF MET-230 IN INTRAMOLECULAR ELECTRON TRANSFER BETWEEN THE OXYFERRYL HEME AND TRP 191 IN CYTOCHROME C PEROXIDASE COMPOUND II

Summary for 2CEP

• Entry DOI: 10.2210/pdb2cep/pdb
• Related: 1BEJ 1BEM 1BEQ 1BES 1CCP 1CPD 1CPE 1CPF 1CPG 2CCP 3CCP 4CCP 5CCP 6CCP 7CCP
• Descriptor: CYTOCHROME C PEROXIDASE, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• Functional Keywords: oxidoreductase(h2o2(a))
• Biological source: Saccharomyces cerevisiae (baker's yeast)
• Cellular location: Mitochondrion matrix: P00431
• Total number of polymer chains: 1
• Total formula weight: 34368.06

Authors

Han, G.W.,Miller, M.A.,Kraut, J. (deposition date: 1994-05-31, release date: 1994-08-31, Last modification date: 2024-02-14)

Primary citation

Liu, R.Q.,Miller, M.A.,Han, G.W.,Hahm, S.,Geren, L.,Hibdon, S.,Kraut, J.,Durham, B.,Millett, F.
Role of methionine 230 in intramolecular electron transfer between the oxyferryl heme and tryptophan 191 in cytochrome c peroxidase compound II.
Biochemistry, 33:8678-8685, 1994

PubMed Abstract: The kinetics of electron transfer from cytochrome c (CC) to yeast cytochrome c peroxidase (CcP) compound I were studied by flash photolysis and stopped-flow spectroscopy. Flash photolysis studies employed horse CC derivatives labeled at specific lysine amino groups with (dicarboxybipyridine)bis-(bipyridine)ruthenium (Ru-CC). Initial electron transfer from Ru-CC reduced the indole radical on Trp-191 of CcP compound I [CMPI(IV,R.)], producing CMPII(IV,R). This reaction was biphasic for each of several Ru-CC derivatives, with rate constants which varied according to the position of the Ru label. For Ru-27-CC labeled at lysine 27, rate constants of 43,000 and 1600 s-1 were observed at pH 5.0 in 2 mM acetate. After reduction of the indole radical by Ru-CC, intramolecular electron transfer from Trp-191 to the oxyferryl heme in CMPII(IV,R) was observed, producing CMPII(III,R.). The rate constant and extent of this intramolecular electron transfer reaction were independent of both the protein concentration and the Ru-CC derivative employed. The rate constant decreased from 1100 s-1 at pH 5 to 550 s-1 at pH 6, while the extent of conversion of CMPII(IV,R) to CMPII(III,R.) decreased from 56% at pH 5 to 29% at pH 6. The reaction was not detected at pH 7.0 and above. The pH dependence of the rate and extent of this internal electron transfer reaction paralleled the pH dependence of the rate of bimolecular reduction of CMPII(IV,R) by native horse CC measured by stopped-flow spectroscopy at high ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

PubMed: 8038157
DOI: 10.1021/bi00195a008

Experimental method

X-RAY DIFFRACTION (2.2 Å)