Interference with the citrulline-based nitric oxide synthase assay by argininosuccinate lyase activity in Arabidopsis extracts.
FEBS J
; 274(16): 4238-45, 2007 Aug.
Article
em En
| MEDLINE
| ID: mdl-17651442
ABSTRACT
There are many reports of an arginine-dependent nitric oxide synthase activity in plants; however, the gene(s) or protein(s) responsible for this activity have yet to be convincingly identified. To measure nitric oxide synthase activity, many studies have relied on a citrulline-based assay that measures the formation of L-citrulline from L-arginine using ion exchange chromatography. In this article, we report that when such assays are used with protein extracts from Arabidopsis, an arginine-dependent activity was observed, but it produced a product other than citrulline. TLC analysis identified the product as argininosuccinate. The reaction was stimulated by fumarate (> 500 microM), implicating the urea cycle enzyme argininosuccinate lyase (EC 4.3.2.1), which reversibly converts arginine and fumarate to argininosuccinate. These results indicate that caution is needed when using standard citrulline-based assays to measure nitric oxide synthase activity in plant extracts, and highlight the importance of verifying the identity of the product as citrulline.
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Base de dados:
MEDLINE
Assunto principal:
Argininossuccinato Liase
/
Citrulina
/
Arabidopsis
/
Óxido Nítrico Sintase
/
Proteínas de Arabidopsis
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article