The unicellular red alga, Cyanidium cddurium, synthesizes phycocyanobilin from protoheme via biliverdin IXa. In vitro transformation of protoheme to biliverdin IXa and biliverdin IXa to phycobilins were previously shown to require NADPH, ferredoxin, and ferredoxin-NADP+ reductase, as well as specific heme oxygenase and phycobilin formation enzymes. The role of NADPH in these reactions was inves...

Characterization of a nitrite reductase-negative Staphylococcus carnosus Tn917 mutant led to the identification of the nir operon, which encodes NirBD, the dissimilatory NADH-dependent nitrite reductase; SirA, the putative oxidase and chelatase, and SirB, the uroporphyrinogen III methylase, both of which are necessary for biosynthesis of the siroheme prosthetic group; and NirR, which revealed n...

Hemoglobin (Hb) potently inactivates the nitric oxide (NO) radical via a dioxygenation reaction forming nitrate (NO(3)(-)). This inactivation produces endothelial dysfunction during hemolytic conditions and may contribute to the vascular complications of Hb-based blood substitutes. Hb also functions as a nitrite (NO(2)(-)) reductase, converting nitrite into NO as it deoxygenates. We hypothesize...

The hepatic microsomal haem oxygenase activity of rats treated with CoCl2 was studied kinetically by measuring biliverdin, the immediate product of the reaction. Biliverdin was extracted with diethyl ether/ethanol mixture, and was determined by the difference between A690 and A800. The apparent Km value for NADPH (at 50 microM-haematin) was about 0.2 microM when an NADPH-generating system was u...

In cyanobacteria, the transcriptional activator NtcA is involved in global nitrogen control and, in the absence of ammonium, regulates the expression of genes involved in the assimilation of alternative nitrogen sources. The oceanic picocyanobacterium Synechococcus sp. strain WH 8103 harbors a copy of ntcA, but in the present study, we show that unlike other marine cyanobacteria that have been ...

Seven known genes control Pseudomonas aeruginosa nitrate assimilation. Three of the genes, designated nas, are required for the synthesis of assimilatory nitrate reductase: nasC encodes a structural component of the enzyme; nasA and nasB encode products that participate in the biosynthesis of the molybdenum cofactor of the enzyme. A fourth gene (nis) is required for the synthesis of assimilator...

Nodulated soybean plants (Glycine max [L.] Merr) were grown in sand culture without combined N or with a continuous supply of nitrate in nutrient solution. Moderate nitrate concentration (30 milligrams N per liter) had little effect on nodule weight/plant while high nitrate concentration (100 milligrams N per liter) depressed nodule weight/plant by 70 to 80% with harvests 30 to 60 days after pl...

We studied the effects of mexidol (3-oxy-6-methyl-2-ethylpiridine succinate) on antioxidant glutathione system in rat brain mitochondria experimental Parkinson’s disease induced by rotenone administration. Wistar rats were divided into following groups 6 each: I - intact (control); II (3 mg/kg per day) was injected subcutaneously for 2 weeks; III after intoxication, (50 intraperitoneally weeks....

Protoplasts purified from pea (Pisum sativum L.) leaves were lysed and fractionated to assess the subcellular distribution of NADPH-dependent hydroxypyruvate reductase (NADPH-HPR) activity. Rate-zonal centrifugation and sucrose-gradient experiments demonstrated that most (about 70%) of the NADPH-HPR activity was located in the supernatant or cytosol fraction. Detectable, but relatively minor ac...