1I54

CYTOCHROME C (TUNA) 2FE:1ZN MIXED-METAL PORPHYRINS

Summary for 1I54

• Entry DOI: 10.2210/pdb1i54/pdb
• Related: 3CYT
• Descriptor: CYTOCHROME C, HEME C, PROTOPORPHYRIN IX CONTAINING ZN, ... (4 entities in total)
• Functional Keywords: cytochrome c, zinc-porphyrin, mixed-metal, electron transport
• Biological source: Thunnus thynnus (bluefin tuna)
• Cellular location: Mitochondrion matrix: P81459
• Total number of polymer chains: 2
• Total formula weight: 25269.26

Authors

Crane, B.R.,Tezcan, F.A.,Winkler, J.R.,Gray, H.B. (deposition date: 2001-02-24, release date: 2001-05-09, Last modification date: 2024-10-30)

Primary citation

Tezcan, F.A.,Crane, B.R.,Winkler, J.R.,Gray, H.B.
Electron tunneling in protein crystals.
Proc.Natl.Acad.Sci.USA, 98:5002-5006, 2001

PubMed Abstract: The current understanding of electron tunneling through proteins has come from work on systems where donors and acceptors are held at fixed distances and orientations. The factors that control electron flow between proteins are less well understood, owing to uncertainties in the relative orientations and structures of the reactants during the very short time that tunneling occurs. As we report here, the way around such structural ambiguity is to examine oxidation-reduction reactions in protein crystals. Accordingly, we have measured and analyzed the kinetics of electron transfer between native and Zn-substituted tuna cytochrome c (cyt c) molecules in crystals of known structure. Electron transfer rates [(320 s(-1) for *Zn-cyt c --> Fe(III)-cyt c; 2000 s(-1) for Fe(II)-cyt c --> Zn-cyt c(+))] over a Zn-Fe distance of 24.1 A closely match those for intraprotein electron tunneling over similar donor-acceptor separations. Our results indicate that van der Waals interactions and water-mediated hydrogen bonds are effective coupling elements for tunneling across a protein-protein interface.

PubMed: 11296248
DOI: 10.1073/pnas.081072898

Experimental method

X-RAY DIFFRACTION (1.5 Å)