ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P146. Key Role of Val567 on L-Arginine Analogues and Heme Ligands
Binding to nNOS.
I. K. Olsbu a , M. Lombard b , H.P. Hersleth a , K.K. Andersson a , J.L. Boucher b
a Department of Molecular Biosciences, University of Oslo, Blindernv. 31, 0371, Oslo, Norway,
b Université Paris Descartes UMR8601 CNRS, Rue st Peres, 75270, Paris, France
e-mail: i.k.Olsbu@imbv.uio.no
Nitric Oxide (NO) is a key inter and intracellular messenger involved in maintenance of vascular tone, neuronal
signalling and immune response in mammals. The biosynthesis of NO involves a two step oxidation of
L-Arginine (L-Arg) to Citrulline and NO by heme thiolate proteins called Nitric Oxide SYntases (NOSs). The
crystallographic studies have revealed a highly conserved hydrophobic pocket among NOSs isoforms, containing
Val, Pro and Phe residues [1]. In bacterial NOSs, this Val residue is change for an Ile residue [2]. THis Val/Ile
swich significantly reduses the rate of NO release due to increased shielding of the heme pocket [3]. and could
alter the reactivity of the heme. Based on these findings, the importanse of this Val567(rat nNOSoxy) residue on
substrtate recognition, heme ligand binding and NO formation was investigated.
Two mutants of nNOSoxy were constructed by point mutation, namely V567S and V567Y and the proteins were
characterised in respect to their binding capability of natural substrates of NOS and substrate analogues, as well
as common heme ligands such as alkylisocyanides and CO
References:
[1] Li H, Shimizu H, Flinspach M, Jamal J, Yang W, Xian M, Cai T, Wen EZ, Jia Q, Wang PG, Poulos TL.
Biochemistry 41 (2002) 13868-13875
[2] Pant K, Bilwes AM, Adak S, Stuehr DJ, Crane BR. Biochemistry 41 (2002) 11071-11079
[3] Wang ZQ, Wei CC, Sharma M, Pant K, Crane BR, Stuehr DJ. J.Biol.Chem. 279 (2004) 19018-19025
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