Substrate-specific interactions with the heme-bound oxygen molecule of nitric-oxide synthase.
We report the characterization by resonance Raman spectroscopy of the oxygenated complex (Fe(II)O(2)) of nitric-oxide synthases of Staphylococcus aureus (saNOS) and Bacillus subtilis (bsNOS) saturated with N(omega)-hydroxy-l-arginine. The frequencies of the nu(Fe-O) and nu(O-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 (nu(Fe-O) at 517 cm(-1) and nu(O-O) at 1123 cm(-1)) and those of substrate-free saNOS (nu(Fe-O) at 517 and nu(O-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 nu(Fe-O) (but not nu(O-O)) upon N(omega)-hydroxy-l-arginine binding as well as the frequency shift of nu(O-O) (but not nu(Fe-O)) upon l-arginine binding. The implications of these substrate-specific interactions with respect to catalysis by NOSs are discussed.
Chartier
François J M
FJ
Département de Biochimie et de Microbiologie and the Centre de Recherche sur la Fonction, la Structure, et l'Ingénierie des Protéines, Université Laval, Quebec City, Quebec G1K 7P4, Canada.
Couture
Manon
M
D001120:Arginine / Q000737:chemistry; D001412:Bacillus subtilis / Q000201:enzymology*; D001671:Biochemistry / Q000379:methods; D002384:Catalysis; D006418:Heme / Q000737:chemistry*; D006860:Hydrogen Bonding; D007700:Kinetics; D008024:Ligands; D008956:Models, Chemical; D019001:Nitric Oxide Synthase / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013053:Spectrophotometry; D013059:Spectrum Analysis, Raman; D013211:Staphylococcus aureus / Q000201:enzymology*; D013379:Substrate Specificity
D008024:Ligands; D006418:Heme; D001120:Arginine; D019001:Nitric Oxide Synthase; D010100:Oxygen