In this study we present evidence that in human erythrocytes NADH-cytochrome b5 reductase (methemoglobin reductase) is not only soluble but also tightly bound to the membrane. The membrane methemoglobin reductase-like activity is unmasked by Triton X-100 treatment, and represents about half of the total activity in the erythrocytes. Like the amphiphilic microsomal-bound cytochrome b5 reductase,...

Sorbitol production in the renal medulla increases in dehydrated rats, indicating that aldose reductase activity varies with the state of hydration. This response could be due to an increased synthesis of the enzyme (Moriyama T et al. J Biol Chem 1989:264:16810-16814) and/or a change in aldose reductase activity caused by acute changes in intracellular ionic composition, ionic strength, osmolal...

Background and objectivesMethylenetetrahydrofolate Reductase (MTHFR) is the critical enzyme in folate 1-carbon metabolism. MTHFR polymorphisms may result increased homocysteine levels, be associated with abnormal lipid metabolism liver. This study aims to explore association between gene of rs1801131 rs1801133 susceptibility nonalcoholic fatty liver disease (NAFLD) coronary artery (CAD).

Incubation of rat hepatocytes with glucagon results in a time- and dose-dependent decrease in the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase. We demonstrate, using immunoprecipitation of radiolabeled enzyme, that 10 nM glucagon inhibits the synthesis of the enzyme by approximately 50%, but that the apparent rate of degradation of the enzyme is not affected by the hormone. We al...

cd(1) nitrite reductase from Pseudomonas stutzeri is a di-haem- containing enzyme, comprising a c-type haem and a d-type haem. Studies with the highly related cd(1) nitrite reductase of Pseudomonas aeruginosa have established that this enzyme undergoes fast (microsecond) and global structural relaxation upon CO photodissociation from the reduced enzyme. A key difference between the Ps. aerugino...

The basolateral handling of 20 microM inorganic mercury (Hg(2+)), in the form of mercuric conjugates of cysteine (Cys), N-acetylcysteine (NAC), or glutathione (GSH), was studied in isolated perfused S2 segments of the rabbit proximal tubule. One of the primary aims of the present study was to determine in a direct manner whether basolateral uptake of Hg(++) occurs in the pars recta of the proxi...

NADPH nitrate reductase activity in higher plants has been attributed to the presence of NAD(P)H bispecific nitrate reductases and to the presence of phosphatases capable of hydrolyzing NADPH to NADH. To determine which of these conditions exist in barley (Hordeum vulgare L. cv. Steptoe), we characterized the NADH and NADPH nitrate reductase activities in crude and affinity-chromatography-purif...

Human glutathione reductase (NADPH + GSSG + H+ in equilibrium with NADP+ + 2 GSH) is a suitable enzyme for correlating spectroscopic properties and chemical reactivities of protein-bound FAD analogues with structural data. FAD, the prosthetic group of the enzyme, was replaced by FAD analogues, which were modified at the positions 8, 1, 2, 4, 5 and 6, respectively, of the isoalloxazine ring. Whe...

Topological analysis with a phoA gene fusion suggested that Acidithiobacillus ferrooxidans MerC, a mercury transporter, has two periplasmic loops and four transmembrane domains. Cys-23 and Cys-26 of the protein were involved in Hg(2+)-recognition/uptake, but Cys-132 and Cys-137 were not. Escherichia coli cells producing the MerC were hypersensitive to CdCl(2). In this case, mutation of His72 re...

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at...