Malate dehydrogenase activation

Malate dehydrogenase activity would be expected in intact mitochondria, but not in SMPs. The activity of this enzyme in mitochondrial fractions may be estimated by a spectrophotometric assay. Oxaloacetate and NADH are incubated, and the disappearance of NADH is monitored at 340 nm. NAD+ does not have strong absorption at this wavelength. Note that the reverse reaction is studied because the reaction as shown above is very unfavorable in thermodynamic terms ACT = +30 kj/mol). 

Explain the derivation of Equation El0.4 for malate dehydrogenase activity calculation. 

Dietary amaranth in animals results in an exfoliating or solubilizing effect on the brush border membrane of the small intestine. Amaranth stimulates in vitro RNA synthesis by causing the dissociation of chromatin. Amaranth has also been shown to increase kidney malate dehydrogenase activity after intramuscular dosing. 

Arum italicum L spadices were collected in woods near Paris and mitochondria were isolated at various developmental stages and purified on sucrose gradient, according to (1). Cytochrome oxidase and malate dehydrogenase activities were measured by spectrophotometry in a 300 mOsm medium. Tlie ratio of the activities with or without Triton X-100 (0,2%) give an estimation of outer membrane permeability to cytochrome c or of inner membrane permeability to NADH. and thus of mitochondrial integrity. Lipids were extracted and analysed according to (3) and separated by TLC... 

On the other hand, the inner membrane integrity, measured as the permeability to NADH (malate dehydrogenase activity) did not change during the development of the inflorescence. 

FIGURE 20,20 (a) The structure of malate dehydrogenase, (b) The active site of malate dehydrogenase. Malate is shown in red NAD" is blue. 

Signs of nickel deficiency in the laboratory white rat (Rattus sp.) include retarded growth, anemia, a reduction in hematocrit and hemoglobin values, decreased enzyme activities (malate dehydrogenase, glucose-6-phosphate dehydrogenase, alpha amylase), a reduction in liver total lipids... 

In this pathway the electrons for the drug reduction are generated by the oxidative decarboxylation of malate catalyzed by the NAD-dependent malic enzyme (malate dehydrogenase (decarboxylating)). The NADH produced by this reaction is reoxidized by an enzyme with NADH ferredoxin oxidoreductase activity that has been recently identified as a homologue of the NADH dehydrogenase (NDH) module of the mitochondrial respiratory complex I (Hrdy et al. 2004 and see Hrdy et al., this volume). The... 

---