TY - JOUR
T1 - Mechanism of Inactivation of Neuronal Nitric Oxide Synthase by (S)-2-Amino-5-(2-(methylthio)acetimidamido)pentanoic Acid
AU - Tang, Wei
AU - Li, Huiying
AU - Doud, Emma H.
AU - Chen, Yunqiu
AU - Choing, Stephanie
AU - Plaza, Carla
AU - Kelleher, Neil L.
AU - Poulos, Thomas L.
AU - Silverman, Richard B.
N1 - Publisher Copyright:
© 2015 American Chemical Society.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2015/5/13
Y1 - 2015/5/13
N2 - Nitric oxide synthase (NOS) catalyzes the conversion of L-arginine to L-citrulline and the second messenger nitric oxide. Three mechanistic pathways are proposed for the inactivation of neuronal NOS (nNOS) by (S)-2-amino-5-(2-(methylthio)acetimidamido)pentanoic acid (1): sulfide oxidation, oxidative dethiolation, and oxidative demethylation. Four possible intermediates were synthesized. All compounds were assayed with nNOS, their IC50, KI, and kinact values were obtained, and their crystal structures were determined. The identification and characterization of the products formed during inactivation provide evidence for the details of the inactivation mechanism. On the basis of these studies, the most probable mechanism for the inactivation of nNOS involves oxidative demethylation with the resulting thiol coordinating to the cofactor heme iron. Although nNOS is a heme-containing enzyme, this is the first example of a NOS that catalyzes an S-demethylation reaction; the novel mechanism of inactivation described here could be applied to the design of inactivators of other heme-dependent enzymes.
AB - Nitric oxide synthase (NOS) catalyzes the conversion of L-arginine to L-citrulline and the second messenger nitric oxide. Three mechanistic pathways are proposed for the inactivation of neuronal NOS (nNOS) by (S)-2-amino-5-(2-(methylthio)acetimidamido)pentanoic acid (1): sulfide oxidation, oxidative dethiolation, and oxidative demethylation. Four possible intermediates were synthesized. All compounds were assayed with nNOS, their IC50, KI, and kinact values were obtained, and their crystal structures were determined. The identification and characterization of the products formed during inactivation provide evidence for the details of the inactivation mechanism. On the basis of these studies, the most probable mechanism for the inactivation of nNOS involves oxidative demethylation with the resulting thiol coordinating to the cofactor heme iron. Although nNOS is a heme-containing enzyme, this is the first example of a NOS that catalyzes an S-demethylation reaction; the novel mechanism of inactivation described here could be applied to the design of inactivators of other heme-dependent enzymes.
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U2 - 10.1021/jacs.5b01202
DO - 10.1021/jacs.5b01202
M3 - Article
C2 - 25874809
AN - SCOPUS:84929376723
VL - 137
SP - 5980
EP - 5989
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 18
ER -