Improvements of the Nitrite Color Development in Assays of Nitrate Reductase by Phenazine Methosulfate and Zinc Acetate 1
AUTOR(ES)
Scholl, R. L.
RESUMO
Nitrate reductase activity is most commonly assayed by measurement of product formation. Excess NADH and factor(s) present in the enzyme extract that interfere with the diazotization and azo color complex of nitrite cause a depression of apparent nitrate reductase activity. Two postassay treatments were found that markedly enhanced the extent of nitrite color formation and apparent nitrate reductase activity. The procedure involves stopping the reaction with zinc acetate (50 μmoles per ml of reaction mix), followed by removal of the precipitate by centrifugation. Presumably the zinc acetate removes extract factor(s) that interfere with color development, because it does not remove the NADH. Phenazine methosulfate (15 nmoles per ml of reaction mix) is added to aliquots of the supernatant and allowed to stand for 20 min at 30 C to oxidize the residual NADH before color development.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=541456Documentos Relacionados
- Comparative Induction of Nitrate Reductase by Nitrate and Nitrite in Barley Leaves 1
- PHOTOREDUCTION OF UBIQUINONE AND PHOTOOXIDATION OF PHENAZINE METHOSULFATE BY CHROMATOPHORES OF PHOTOSYNTHETIC BACTERIA AND BACTERIOCHLOROPHYLL*
- Generation of free radicals from phenazine methosulfate, streptonigrin, and riboflavin in bacterial suspensions.
- Nitrate and Nitrite Reduction by Wolffia arrhiza1
- The Conversion of Nitrite to Nitrogen Oxide(s) by the Constitutive NAD(P)H-Nitrate Reductase Enzyme from Soybean 1