Substrate-specific Interactions with the Heme-bound Oxygen Molecule of Nitric-oxide Synthase

• Published in: The Journal of biological chemistry 2007-07, Vol.282 (29), p.20877-20886
• Main Authors: Chartier, François J.M., Couture, Manon
• Format: Article
• Language: English
• Subjects: Arginine - chemistry; Bacillus subtilis; Bacillus subtilis - enzymology; Biochemistry - methods; Catalysis; Heme - chemistry; Hydrogen Bonding; Kinetics; Ligands; Models, Chemical; Nitric Oxide Synthase - chemistry; Oxygen - chemistry; Spectrophotometry; Spectrum Analysis, Raman; Staphylococcus aureus; Staphylococcus aureus - enzymology; Substrate Specificity
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M701800200

We report the characterization by resonance Raman spectroscopy of the oxygenated complex (FeIIO2) of nitric-oxide synthases of Staphylococcus aureus (saNOS) and Bacillus subtilis (bsNOS) saturated with Nω-hydroxy-l-arginine. The frequencies of the νFe–O and νO–O modes were 530 and 1135 cm–, respectively, in both the presence and absence of tetrahydrobiopterin. On the basis of a comparison of these frequencies with those of saNOS and bsNOS saturated with l-arginine (νFe–O at 517 cm–1 and νO–O at 1123 cm–1) and those of substrate-free saNOS (νFe–O at 517 and νO–O at 1135 cm–1) (Chartier, F. J. M., Blais, S. P., and Couture, M. (2006) J. Biol. Chem. 281, 9953–9962), we propose two models that account for the frequency shift of νFe–O (but not νO–O) upon Nω-hydroxy-l-arginine binding as well as the frequency shift of νO–O (but not νFe–O) upon l-arginine binding. The implications of these substrate-specific interactions with respect to catalysis by NOSs are discussed.