Activities of some enzymes related to carbon metabolism were studied in different ecotypes of Rumex nepalensis growing at 1 300, 2 250, and 3 250 m above mean sea level. Activities of ribulose-1,5-bisphosphate carboxylase/oxygenase, phosphoenolpyruvate carboxylase, aspartate aminotransferase, and glutamine synthetase increased with altitude, whereas activities of malate dehydrogenase, NAD-malic enzyme, and citrate synthase did not show a significant difference with change in altitude. and N. Kumar ... [et al.].
L-malate, a tricarboxylic acid cycle (TCA ) intermediate, plays an important role in transporting NADH from cytosol to mitochondria for energy production and may be involved in the beneficial effects of improving physical stamina. In the present study, we investigated the effects of L-malate on the performance of forced swimming time and blood biochemical parameters related to fatigue – blood urea nitrogen (BUN), glucose (Glc), creatine kinase (CK) , total protein (TP) and lactic acid (LA). To investigate the effects of L-malate on the malate-aspartate shuttle and energy metabolism in mice, the activities of enzymes related to the malate-aspartate shuttle were measured. L-malate was orally administered to mice continuously for 30 days using a feeding atraumatic needle. The swimming time was increased by 26.1 % and 28.5 %, respectively, in the 0.210 g/kg and 0.630 g/kg L-malate-treated group compared with the control group. There were no differences in the concentrations of Glc, BUN and TP between the L-malate-treated groups and the control groups. However, the levels of CK were significantly decreased in the L-malate-treated groups. The results predict a potential benefit of L-malate for improving physical stamina and minimizing muscle damage during swimming exercise. The activities of cytosolic and mitochondrial malate dehydrogenase were significantly elevated in the L-malate-treated group compared with the control group. These enzymatic activities may be useful indicators for evaluating changes affecting the malate-aspartate shuttle and energy metabolism in the liver of mice., J. L. Wu, Q. P. Wu, J. M. Huang, R. Chen, M. Cai, J. B. Tan., and Obsahuje bibliografii a bibliografické odkazy
Malate dehydrogenase (EC 1.1,1,37.) (MDH) was purified to apparent homogeneity from the cytosolic fraction of the protozoan Trichomonas vaginalis Donné. The four step purification included ion-exchange chromatography (DEAE-Sephacel and Q-Sepharose, elution with NaCl) and affinity chromatography (Reactive Red Agarose, elution with NADH and NaCl). The enzyme was purified about 132-fold (30.6% yield) to a specific activity of 352 units mg~'. The Km values determined at pH 7.8 (pH optimum from 7.5 to 8.3) for oxaloacetate and NADH were 16.2 pM and 10.6 μΜ, respectively. The MDH activity was inhibited by the substrate, decreasing to 50% at about 1 mM concentration of oxaloacetate. The reverse reaction from malate to oxaloacetate showed a pH optimum around pH 9.5. The Km for malate and NAD* (determined at pH 7.8) were 1220 pM and 69.9 pM, respectively. SDS-PAGE analysis of the purified MDH revealed a single band with an apparent size of 34.5 kDa. The native molecular weight was estimated by HPLC gel filtration to be 60 kDa, which indicates that the T. vaginalis MDH exists as a dimer.
A low irradiance mediated regulation of C4 metabolism during acclimation is reported for first time in Amaranthus hypochondriacus L., a NAD-ME dicot, Eleusine coracana (L.) Gaertn., an NAD-ME monocot, and Gomphrena globosa, a NADP-ME dicot. Significant decline in activities of key C4 enzymes were observed under limited irradiances in each of the species studied. When the plants were transferred to full natural irradiance, the enzyme activities were restored to originál State in 3-5 d, a similar time frame needed for acclimation to limiting irradiance. This identifies the decarboxylation reaction involving NAD-ME in Amaranthus and Eleusine or NADP-ME in Gomphrena as crucial sites of regulation under limiting irradiance.