Malate dehydrogenase dissociation

Malate dehydrogenase from H. marismortui (AMDH) is the halophilic protein that has been studied most by solution structure methods. A molar mass of 87 kg/mol was determined for the native enzyme. It is stable at high concentrations of NaCl or KC1 and unfolds and dissociates below 2.5 M salt. Pundak and Eisenberg (1981) first measured values for the solvent interactions of AMDH and found that, in contrast to nonhalophilic globular proteins in similar conditions (Bi 0.2—0.3 g/g,B3 0.01 g/g),the halophilic protein bound... 

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. 

Q. This finding eliminates a truly rapid equilibrium random mechanism, for which k and k must be much smaller than fc 4, k-i, k, and k-2, since the two exchange rates must then be equal. In fact, the differences between the two exchange rates show that the dissociation of A and/or P from the ternary complexes must be slow compared with that of B and/or Q, and also slow relative to the interconversions of the ternary complexes (32). This means that in at least one direction of reaction the dissociation of products in the overall reaction is essentially ordered for all these enzymes, the coenzymes dissociating last, as in the preferred pathway mechanism (Section I,B,4). With malate, lactate, and liver alcohol dehydrogenases, the NAD/NADH exchange rate increased to a... 

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