A conformational study on the intermediates along the synthetic pathway of nitric oxide (NO) formation by NO synthase

M. B. Santillán, G. M. Ciuffo, E. A. Jáuregui, I. Csizmadia

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The recent discovery that nitric oxide (NO) plays a role as a second messenger in biological processes created a growing interest in this radical, which is synthesized from one of the terminal nitrogen atoms of L-Arginine, denoted as species A. In the present paper we report a full configurational and conformational study performed by means of AM1 calculations on model compound intermediates (species B, C, D and E) on the synthetic pathway of nitric oxide formation. We obtained fully optimized structures for these molecules. Relatively few conformations were found for species A, B, C and F (L-citrulline). Species D became an interesting conformational problem because of the presence of a triatomic CNO ring associated with C3. In this three-membered ring the carbon becomes a chiral center for this molecule. Although more than 200 conformations were analyzed, we observed a clear tendency of these starting points to rearrange to a relatively few (34) final conformations. As expected, conformational as well as chiral enantiomers were obtained for both C3[R] and C3[S] enantiomers, with comparable energies. Species E yield the S enantiomer on C3 as the most frequently observed conformations, but the two lowest-energy conformations were comparable for the C3[R] and C3[S] enantiomers. Changes observed on the distances between the C···O and C···N atoms fully justify the proposed mechanism. Similarly, changes on the atomic charges on N4 also supports the mechanism involving the scission of the C···N bond and the formation of a C=O double bond, which leads to the formation of citrulline (species F).

Original languageEnglish
Pages (from-to)237-250
Number of pages14
JournalJournal of Molecular Structure: THEOCHEM
Volume463
Issue number3
DOIs
Publication statusPublished - May 3 1999

Fingerprint

Citrulline
enantiomers
Nitric oxide
nitric oxide
Nitric Oxide Synthase
Enantiomers
Conformations
Nitric Oxide
Biological Phenomena
Second Messenger Systems
Carbon Monoxide
Arginine
Nitrogen
Carbon
rings
Atoms
Molecules
nitrogen atoms
molecules
cleavage

Keywords

  • Conformational study
  • Nitric oxide
  • Reaction mechanism

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Computational Theory and Mathematics
  • Atomic and Molecular Physics, and Optics

Cite this

A conformational study on the intermediates along the synthetic pathway of nitric oxide (NO) formation by NO synthase. / Santillán, M. B.; Ciuffo, G. M.; Jáuregui, E. A.; Csizmadia, I.

In: Journal of Molecular Structure: THEOCHEM, Vol. 463, No. 3, 03.05.1999, p. 237-250.

Research output: Contribution to journalArticle

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