Spinach Nitrate Reductase : Effects of Ionic Strength and pH on the Full and Partial Enzyme Activities.

Initial velocity studies of immunopurified spinach nitrate reductase have been performed under conditions of controlled ionic strength and pH and in the absence of chloride ions. Increased ionic strength stimulated NADH:ferricyanide reductase and reduced flavin:nitrate reductase activities and inhibited NADH:nitrate reductase, NADH:cytochrome c reductase and reduced methyl viologen:nitrate reductase activities. NADH:dichlorophenolindophenol reductase activity was unaffected by changes in ionic strength.

Oxidation--reduction midpoint potentials of the flavin, haem and Mo-pterin centres in spinach (Spinacia oleracea L.) nitrate reductase.

Oxidation-reduction midpoint potentials have been determined for the flavin, cytochrome b557 and Mo-pterin prosthetic groups of spinach (Spinacia oleracea L.) assimilatory nitrate reductase using visible, c.d.

Chloride inhibition of spinach nitrate reductase.

Initial rate studies of spinach (Spinacia oleracea L.) nitrate reductase showed that NADH:nitrate reductase activity was ionic strength dependent with elevated ionic concentration resulting in inhibition. In contrast, NADH:ferricyanide reductase was markedly less ionic strength dependent.

Oxidation-reduction midpoint potentials of the molybdenum center in spinach NADH:nitrate reductase.

Oxidation-reduction midpoint potentials for the molybdenum center in assimilatory NADH:nitrate reductase isolated from spinach (Spinacia oleracea) have been determined at pH 7.0 in the presence of dye mediators using EPR spectroscopy to monitor formation of Mo(V). Values for the Mo(VI)/Mo(V) and Mo(V)/Mo(IV) couples were determined to be -8 and -42 mV, respectively.

Monoclonal antibodies to a higher-plant nitrate reductase: Differential inhibition of enzyme activities.

A set of monoclonal antibodies has been raised against NADH-nitrate reductase (NR; EC 1.6.6.

Studies by electron-paramagnetic-resonance spectroscopy of the molybdenum centre of spinach (Spinacia oleracea) nitrate reductase.

The molybdenum centre of spinach (Spinacia oleracea) nitrate reductase has been investigated by e.p.r.

The reactivation of nitrate reductase from spinach (Spinacea oleracea L.) inactivated by NADH and cyanide: effects of peroxidase and associated systems.

Nitrate reductase of spinach (Spinacea oleracea L.) leaves which had been inactivated in vitro by treatment with NADH and cyanide, was reactivated by incubation with oxidant systems and measured as FMNH2-dependent activity. Ferricyanide, a purely chemical oxidant, produced rapid maximal reactivation (100%) which was 90% complete in less than 3 min.

The reactivation of nitrate reductase from spinach (Spinacia oleracea L.) inactivated by NADH and cyanide, using trivalent manganese either generated by illuminated chloroplasts or as manganipyrophosphate.

Nitrate reductase of spinach (Spinacia oleracea L.) leaves which had been inactivated in vitro by treatment with NADH and cyanide, was reactivated by incubation with oxidant systems and measured as FMNH2-dependent activity. Reactivation was produced with trivalent manganese compounds represented either by manganipyrophosphate or produced by oxidation of Mn(2+) ions in the presence of illuminated chloroplasts and compared with reactivation obtained with ferricyanide.

The amino acid sequence of cytochrome c from Abutilon theophrasti Medic. and Gossypium barbadense L. (cotton).

The amino acid sequences of Abutilon and Gossypium cytochromes c were determined on 1mumol of protein. The molecules consist of 111 residues and are homologous with other mitochondrial plant cytochromes c. Experimental details are given in a supplementary paper that has been deposited as Supplementary Publication SUP 50005 at the National Lending Library for Science and Technology, Boston Spa, Yorks.

Generation of extramitochondrial reducing power in gluconeogenesis.

1. Kidney-cortex slices incubated with pyruvate formed glucose and lactate in relatively large and approximately equimolar quantities. The formation of these products involves two exclusively cytoplasmic NADH(2)-requiring reductions, catalysed by lactate dehydrogenase and triose phosphate dehydrogenase.

Gluconeogenesis in mouse-liver slices.

1. The rate of gluconeogenesis from amino acids and other known precursors in slices of mouse liver after depletion of liver glycogen by means of phlorrhizin was high with l-lactate, pyruvate, glycerol, d-glyceraldehyde, dihydroxyacetone, d-fructose, sorbitol, xylitol, alpha-glycerophosphate, alanine, proline, threonine, serine and propionate. 2.