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Published November 16, 2005 | Supplemental Material
Journal Article Open

Picosecond Photoreduction of Inducible Nitric Oxide Synthase by Rhenium(I)−Diimine Wires

Abstract

In a continuing effort to unravel mechanistic questions associated with metalloenzymes, we are developing methods for rapid delivery of electrons to deeply buried active sites. Herein, we report picosecond reduction of the heme active site of inducible nitric oxide synthase bound to a series of rhenium−diimine electron-tunneling wires, [Re(CO)_3LL']^+, where L is 4,7-dimethylphenanthroline and L' is a perfluorinated biphenyl bridge connecting a rhenium-ligated imidazole or aminopropylimidazole to a distal imidazole (F_8bp-im (1) and C_3-F_8bp-im (2)) or F (F_9bp (3) and C_3-F_9bp (4)). All four wires bind tightly (K_d in the micromolar to nanomolar range) to the tetrahydrobiopterin-free oxidase domain of inducible nitric oxide synthase (iNOSoxy). The two fluorine-terminated wires displace water from the active site, and the two imidazole-terminated wires ligate the heme iron. Upon 355-nm excitation of iNOSoxy conjugates with 1 and 2, the active site Fe(III) is reduced to Fe(II) within 300 ps, almost 10 orders of magnitude faster than the naturally occurring reduction.

Additional Information

© 2005 American Chemical Society. Received 29 June 2005. Published online 19 October 2005. Published in print 1 November 2005. This research was supported by NIH (DK19038; GM070868), the Parsons Foundation (W.B.-B.), the Fannie and John Hertz Foundation (A.R.D.), the Ellison Medical Foundation (Senior Scholar Award in Aging to H.B.G.), and the Arnold and Mabel Beckman Foundation.

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August 19, 2023
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