Nitrate assimilation in many plants, algae, yeasts and bacteria is mediated by two enzymes, nitrate reductase (EC 1.6.6.2) and nitrite reductase (EC 1.7.7.1). They catalyse the stepwise reduction of nitrate to nitrite and nitrite to ammonia respectively. The nitrite reductase from an industrially important yeast, Candida utilis, has been purified to homogeneity. Purified nitrite reductase is a ...

Isoelectric Focusing, Nitrate Reductase, Diaphorase, Chlamydomonas reinhardii Chlamydomonas reinhardii 104 mutant strain cells contain many NAD(P)H-cytochrom e c reductase activities unrelated to nitrate reduction in addition to an NAD(P)H-cytochrom e c reductase related to NAD(P)H-nitrate reductase, which have molecular weights from 37000 to 124000. By combining chromatographic procedures and ...

Nitrate reductase (nar) A, B and E mutants of Escherichia coli with plasmids carrying Klebsiella pneumoniae nitrogen fixation (nif) genes reduced acetylene independently of added molybdate, but nar D mutants showed pleiotropic dependence on the concentration of added molybdate for expression of both nar and nif. No complementation of nar mutations by nif occurred; nitrite but not nitrate repres...

The influence of nutrient nitrate level (0-20 millimolar) on the effects of NO(2) (0-0.5 parts per million) on growth, K, photosynthetic pigment, N contents, and the activities of enzymes of N assimilation was studied in bean (Phaseolus vulgaris L. cv Kinghorn Wax) leaves. Exposing 7-day old bean seedlings for 5 days continuously to 0.02 to 0.5 parts per million NO(2) increased plant height, fr...

The mhsm underying the sharp increase in activity of nitrate reductase (EC 1.6.6.1) in Chlorefi vulgars forma terdis (strain 211 8k) during the first hour of the 7 hours/5 hours Light/dark cycle was investigated. Using the method of density labelng and isopycnic centaton, It could be trated that this rapi increase in activity is based on ligt-mediated activation ratber than denovo synthesis of ...

chlD mutants of Escherichia coli lack active nitrate reductase but form normal levels of this enzyme when the medium is supplemented with 10-3 M molybdate. When chlD mutants were grown in unsupplemented medium and then incubated with molybdate in the presence of chloramphenicol, they formed about 5% the normal level of nitrate reductase. Some chlD mutants or the wild type grown in medium supple...

Huge quantities of pesticides are dispersed in the environment, affecting non-target organisms. Since paraquat affects the photosynthetic process, the biochemical composition of affected species should be altered. The effect of paraquat on Chlamydomonas moewusii, a freshwater non-target species, was studied. After 48 h of herbicide exposure, growth rate, dry weight, and chlorophyll a and protei...