Implications for isoform-selective inhibitor design derived from the binding mode of bulky isothioureas to the heme domain of endothelial nitric-oxide synthase.
Nitric oxide produced by nitric-oxide synthase (NOS) is not only involved in a wide range of physiological functions but also in a variety of pathological conditions. Isoform-selective NOS inhibitors are highly desirable to regulate the NO production of one isoform beneficial to normal physiological functions from the uncontrolled NO production of another isoform that accompanies certain pathological states ...
Nitric oxide produced by nitric-oxide synthase (NOS) is not only involved in a wide range of physiological functions but also in a variety of pathological conditions. Isoform-selective NOS inhibitors are highly desirable to regulate the NO production of one isoform beneficial to normal physiological functions from the uncontrolled NO production of another isoform that accompanies certain pathological states. Crystal structures of the heme domain of the three NOS isoforms have revealed a very high degree of similarity in the immediate vicinity of the heme active site illustrating the challenge of isoform-selective inhibitor design. Isothioureas are potent NOS inhibitors, and the structures of the endothelial NOS heme domain complexed with isothioureas bearing small S-alkyl substituents have been determined (Li, H., Raman, C.S., Martásek, P., Král, V., Masters, B.S.S., and Poulos, T.L. (2000) J. Inorg. Biochem. 81, 133--139). In the present communication, the binding mode of larger bisisothioureas complexed to the endothelial NOS heme domain has been determined. These structures afford a structural rationale for the known inhibitory activities. In addition, these structures provide clues on how to exploit the longer inhibitor substituents that extend out of the active site pocket for isoform-selective inhibitor design.
Related Citations:
Crystal Structure of Constitutive Endothelial Nitric Oxide Synthase: a Paradigm for Pterin Function Involving a Novel Metal Center Raman, C.S., Li, H., Martasek, P., Kral, V., Masters, B.S., Poulos, T.L. (1998) Cell 95: 939
Structure of Nitric Oxide Synthase Oxygenase Dimer with Pterin and Substrate Crane, B.R., Arvai, A.S., Ghosh, D.K., Wu, C., Getzoff, E.D., Stuehr, D.J., Tainer, J.A. (1998) Science 279: 2121
Organizational Affiliation:
Department of Molecular Biology & Biochemistry, University of California, Irvine, California 92697, USA.
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