2BCN

Solvent isotope effects on interfacial protein electron transfer between cytochrome c and cytochrome c peroxidase

Summary for 2BCN

• Entry DOI: 10.2210/pdb2bcn/pdb
• Descriptor: cytochrome c peroxidase, Cytochrome c iso-1, PROTOPORPHYRIN IX CONTAINING ZN, ... (5 entities in total)
• Functional Keywords: protein-protein complex, oxidoreductase-electron transfer complex, oxidoreductase/electron transfer
• Biological source: Saccharomyces cerevisiae (baker's yeast); More
• Cellular location: Mitochondrion intermembrane space: P00044
• Total number of polymer chains: 3
• Total formula weight: 81467.59

Authors

Kang, S.A.,Crane, B.R. (deposition date: 2005-10-19, release date: 2006-02-28, Last modification date: 2024-12-25)

Primary citation

Kang, S.A.,Hoke, K.R.,Crane, B.R.
Solvent isotope effects on interfacial protein electron transfer in crystals and electrode films.
J.Am.Chem.Soc., 128:2346-2355, 2006

PubMed Abstract: D(2)O-grown crystals of yeast zinc porphyrin substituted cytochrome c peroxidase (ZnCcP) in complex with yeast iso-1-cytochrome c (yCc) diffract to higher resolution (1.7 A) and pack differently than H(2)O-grown crystals (2.4-3.0 A). Two ZnCcP's bind the same yCc (porphyrin-to-porphyrin separations of 19 and 29 A), with one ZnCcP interacting through the same interface found in the H(2)O crystals. The triplet excited-state of at least one of the two unique ZnCcP's is quenched by electron transfer (ET) to Fe(III)yCc (k(e) = 220 s(-1)). Measurement of thermal recombination ET between Fe(II)yCc and ZnCcP+ in the D(2)O-treated crystals has both slow and fast components that differ by 2 orders of magnitude (k(eb)(1) = 2200 s(-1), k(eb)(2) = 30 s(-1)). Back ET in H(2)O-grown crystals is too fast for observation, but soaking H(2)O-grown crystals in D(2)O for hours generates slower back ET, with kinetics similar to those of the D(2)O-grown crystals (k(eb)(1) = 7000 s(-1), k(eb)(2) = 100 s(-1)). Protein-film voltammetry of yCc adsorbed to mixed alkanethiol monolayers on gold electrodes shows slower ET for D(2)O-grown yCc films than for H(2)O-grown films (k(H) = 800 s(-1); k(D) = 540 s(-1) at 20 degrees C). Soaking H(2)O- or D(2)O-grown films in the counter solvent produces an immediate inverse isotope effect that diminishes over hours until the ET rate reaches that found in the counter solvent. Thus, D(2)O substitution perturbs interactions and ET between yCc and either CcP or electrode films. The effects derive from slow exchanging protons or solvent molecules that in the crystal produce only small structural changes.

PubMed: 16478190
DOI: 10.1021/ja0557482

Experimental method

X-RAY DIFFRACTION (1.7 Å)