title: Inactivation of sunflower NADH:nitrate reductase by white light-activated rose bengal.
abstract: Chemical modification of purified nitrate reductase (NR) from sunflower leaves by white light-irradiated rose bengal was studied. NADH:NR activity was inhibited by light-activated rose bengal in both a concentration- and time-dependent manner. MV:NR activity was less sensitive to inhibition than NADH:NR activity, especially when the enzyme was preincubated with NADH. Preincubation of the enzyme with FAD protected inhibition of NADH:NR activity but not the MV:NR activity. These results suggest that sunflower NR contains sensitive histidine residue which interacts with reduced FAD during catalytic electron transfer. Most importantly, NADH-reduced NR was more sensitive to the irradiated dye, indicating that conformation of the oxidized and reduced enzyme forms were different.
authors.affiliation: Division of Biochemistry, Indian Agricultural Research Institute, New Delhi.
authors.forename: D
authors.initials: D
authors.lastname: Pattanayak
authors.forename: S R
authors.initials: SR
authors.lastname: Chatterjee
mesh_terms: D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes / Q000494:pharmacology*; D006368:Helianthus / Q000201:enzymology*; D008027:Light; D050895:Nitrate Reductase (NADH); D009565:Nitrate Reductases / Q000037:antagonists & inhibitors*; D012395:Rose Bengal / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D012395:Rose Bengal; D009565:Nitrate Reductases; D050895:Nitrate Reductase (NADH)