| Reactivity of amino acids in nitrosation reactions and its relation to the alkylating potential of their products. | |
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MedLine Citation:
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PMID: 11878971 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Nitrosation reactions of amino acids with an -NH(2) group [namely, six alpha-amino acids (glycine, alanine, alpha-aminobutyric acid, alpha-aminoisobutyric acid, valine, and norvaline); two beta-amino acids (beta-alanine and beta-aminobutyric acid), and one gamma-amino acid (gamma-aminobutyric acid)] were studied. Nitrosation was carried out in aqueous acid media, mimicking the conditions of the stomach lumen. The rate equation was r = k(3)(exp)[amino acid][nitrite](2), with a maximum k(3)(exp) value in the 2.3-2.7 pH range. The existence of an isokinetic relationship supports the argument that all the reactions share a common mechanism. A nitrosation mechanism is proposed, and the following conclusions are drawn: (i) Nitrosation reactions of amino acids with a primary amino group in acid media occur with dinitrogen trioxide as the main nitrosating agent. The finding that the nitrosation rate is proportional to the square of the nitrite concentration suggests that the yield of nitrosation products in the stomach would increase sharply with higher nitrate/nitrite intakes. (ii) Stomach hypochlorhydria could be a potential enhancer of in vivo amino acid nitrosation. (iii) The reactivity (k(3)()(exp)) [alpha-amino acids > beta-amino acids > gamma-amino acids] is the same as that found in a previous work for the alkylating potential of lactones formed from nitrosation products of the same amino acids. This implies that the nitrosation reactions of the most common natural amino acids are the most efficient precursors of the most powerful alkylating agents. (iv) The order of magnitude (10(7)-10(8) M(-1) s(-1)) of the bimolecular rate constants of nitrosation shows that such reactions occur through an encounter process. |
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Authors:
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M del Pilar García-Santos; Samuel González-Mancebo; Jesús Hernández-Benito; Emilio Calle; Julio Casado |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of the American Chemical Society Volume: 124 ISSN: 0002-7863 ISO Abbreviation: J. Am. Chem. Soc. Publication Date: 2002 Mar |
Date Detail:
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Created Date: 2002-03-06 Completed Date: 2002-07-01 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 7503056 Medline TA: J Am Chem Soc Country: United States |
Other Details:
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Languages: eng Pagination: 2177-82 Citation Subset: IM |
Affiliation:
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Departamento de Química Física, Universidad de Salamanca, E-37008 Salamanca, Spain. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Alkylating Agents
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chemical synthesis*,
chemistry Amino Acids / chemistry* Kinetics Nitrosation Sodium Nitrite / chemistry* |
| Chemical | |
Reg. No./Substance:
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0/Alkylating Agents; 0/Amino Acids; 7632-00-0/Sodium Nitrite |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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