In 27 C4 grasses grown under adequate or deficient nitrogen (N) supplies, N-use efficiency at the photosynthetic (assimilation rate per unit leaf N) and whole-plant (dry mass per total leaf N) level was greater in NADP-malic enzyme (ME) than NAD-ME species. This was due to lower N content in NADP-ME than NAD-ME leaves because neither assimilation rates nor plant dry mass differed significantly ...

Light-dependent O(2) reduction concomitant with O(2) evolution, ATP formation, and NADP reduction were determined in isolated spinach (Spinacia oleracea L. var. America) chloroplast lamellae fortified with NADP and ferredoxin. These reactions were investigated in the presence or absence of catalase, providing a tool to estimate the reduction of O(2) to H(2)O(2) (Mehler reaction) concomitant wit...

Abstract Aluminum (Al) is an important factor that limits plant growth under acidic soil conditions. However, several species developed distinct mechanisms limit the damage caused by high Al concentrations. In highbush blueberry (Vaccinium corymbosum), resistance are not fully understood. This study was designed to evaluate effect of toxicity on roots and leaves genotypes with contrasting [Star...

glucose 6-phosphate dehydrogenase (g6pd) was purified from streptomyces aureofaciens and inactivated with butanedione and diethylpyrocarbonate. incubation of the enzyme with butanedione resulted in a rapid activity loss (80%) within 5 min, followed by a slow phase using a molar ratio to enzyme concentration of 100. fluorescence studies showed a conformational change in the butanedione-modified ...

Addition of NADP(+) to thylakoid membranes or isolated photosystem I (PSI) submembrane fractions quenched chlorophyll fluorescence by up to 40% at low or room temperature. This quenching was reversed by NADPH. Similar quenching was also observed with the addition of heparin or thenoyltrifluoroacetone (TTFA), inhibitors that bind ferredoxin:NADP(+) reductase (FNR) and prevent reduction of NADP(+...

The steady state kinetic mechanisms for glucose-6-P dehydrogenase from lactating rat mammary glands were derived for the NADP-linked and NAD-linked reactions. Initial velocity studies and inhibition patterns using NADPH and glucosamine-6-P are consistent with sequential mechanisms with random order addition of glucose-6-P and coenzyme. No evidence was found for enzyme isomerization or dead-end ...

The effects of divalent salts and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) upon nicotinamide adenine dinucleotide phosphate (NADP) reduction and P700 in isolated chloroplasts are described and compared with the influence of DCMU on oxygen evolution and P700 in intact cells. Most experiments were carried out with a steady-state relaxation spectrometer. A kinetic mechanism for the estimatio...

The light-activated NADP-malate dehydrogenase (NADP-MDH) catalyzes the reduction of oxaloacetate to malate in higher plant chloroplasts. This enzyme is regulated in vivo by the ferredoxin-thioredoxin system through redox reactions. NADP-MDH has been photoactivated in vitro in a chloroplast system reconstituted from the pure protein components and thylakoid membranes. Photoactivation was accompa...

Salt stress is one of the most damaging plant stressors, whereas hypoosmotic stress is not considered to be a dangerous type of stress in plants and has been less extensively studied. This study was performed to compare the metabolism of cucumber plants grown in soil with plants transferred to distilled water and to a 100 mM NaCl solution. Even though hypoosmotic stress caused by distilled wate...