Authors: Sala, Alberto; Nicolis, Stefania; Roncone, Raffaella; Casella, Luigi; Monzani, Enrico

Source: FEBS Journal, Volume 271, Number 13, July 2004 , pp. 2841-2852(12)

Publisher: Wiley-Blackwell

Abstract:

The enzymatic nitration of tryptophan derivatives by oxidation of nitrite has been studied using lactoperoxidase and horseradish peroxidase, and compared with the chemical nitration produced by nitrogen dioxide and peroxynitrite. HPLC, mass spectra and NMR analysis of the mixture of products clearly show that nitration occurs at position 4-, 6-, 7-, and N¹ of the indole ring, and nitrosation at position N¹. Kinetic studies performed on peroxidase/NO₂^-/H₂O₂ systems showed substrate saturation behavior with all the tryptophan derivatives employed. The rate dependence on nitrite concentration was found to be linear with horseradish peroxidase while it exhibited saturation behavior with lactoperoxidase. The composition of the product mixture depends on the nitrating agent. While the production of 4-nitro, 6-nitro, 7-nitro and N¹-nitro derivatives follows a similar trend, indicating that they are formed according to a similar mechanism, the ratio between the N¹-nitroso derivative and other derivatives depends markedly on the nitrite concentration when tryptophan modification is performed by the peroxidase/H₂O₂/nitrite systems. Analysis of the data indicates that at low nitrite concentration the enzymatic reaction occurs through the classical peroxidase cycle. At high nitrite concentration the reaction proceeds through a different intermediate that we assume to be a protein bound peroxynitrite species.

Keywords: heme proteins; nitration; peroxidases; peroxynitrite; tryptophan

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1432-1033.2004.04219.x

Publication date: 2004-07-01

Related content

• In this: publication
• By this: publisher
• In this Subject: Anatomy & Physiology ,  Biology ,  Chemistry (General) ,  Biochemistry
• By this author: Sala, Alberto ;  Nicolis, Stefania ;  Roncone, Raffaella ;  Casella, Luigi ;  Monzani, Enrico

Website © Publishing Technology. Article copyright remains with the publisher, society or author(s) as specified within the article.

• Terms and conditions
• Privacy policy
• Information for advertisers