Picosecond binding of the his ligand to four-coordinate heme in cytochrome c ': A one-way gate for releasing proximal NO

Abstract : We provide a direct demonstration of a "kinetic trap" mechanism in the proximal 5-coordinate heme-nitrosyl complex (5c-NO) of cytochrome c' from Alcaligenes xylosoxidans (AXCP) in which picosecond rebinding of the endogenous His ligand following heme-NO dissociation acts as a one-way gate for the release of proximal NO into solution. This demonstration is based upon picosecond transient absorption changes following NO photodissociation of the proximal 5c-NO AXCP complex. We have determined the absolute transient absorption spectrum of 4-coordinate ferrous heme to which NO rebinds with a time constant tNO = 7 ps (kNO = 1.4 × 1011 s-1) and shown that rebinding of the proximal histidine to the 4-coordinate heme takes place with a time constant tHis = 100 ± 10 ps (kHis = 1010 s-1) after the release of NO from the proximal heme pocket. This rapid His reattachment acts as a one-way gate for releasing proximal NO by precluding direct proximal NO rebinding once it has left the proximal heme pocket and requiring NO rebinding from solution to proceed via the distal heme face. Cop. 2013 American Chemical Society.
Document type :
Journal articles
Complete list of metadatas

https://hal-polytechnique.archives-ouvertes.fr/hal-00817163
Contributor : Denis Roura <>
Submitted on : Thursday, April 25, 2013 - 10:24:58 PM
Last modification on : Wednesday, August 21, 2019 - 3:12:02 PM

Identifiers

Collections

Citation

Byung-Kuk Yoo, Isabelle Lamarre, Jean-Louis Martin, Colin Andrew, Michel Negrerie. Picosecond binding of the his ligand to four-coordinate heme in cytochrome c ': A one-way gate for releasing proximal NO. Journal of the American Chemical Society, American Chemical Society, 2013, 135 (8), pp.3248-3254. ⟨10.1021/ja312140f⟩. ⟨hal-00817163⟩

Share

Metrics

Record views

187