In the presence of oxygen, cells can undergo oxidative phosphorylation to genera

Question

In the presence of oxygen, cells can undergo oxidative phosphorylation to generate ATP. Under anaerobic conditions, such as in muscles undergoing heavy exercise, lactate dehydrogenase is needed to metabolize high levels of pyruvate that accumulate from glycolysis. The figure below shows the active site of the lactate dehydrogenase. Experimental evidence shows that the oxidized NADH binds first to the enzyme followed by lactate. Several residues (aspartic acid and arginine) are involved in the binding of the pyruvate. The transfer of a hydride (from the A face or the Pro R position) occurs quickly followed by dissociation of the lactate and then NAD* from the enzyme. What is the role of the histidine in the lactate dehydrogenase mechanism?

Explanation / Answer

A) In the Lactate Dehydrogenase Mechanism HISTIDINE used. There are also some other residues such as Arginine, glutamate and asparate etc.. The uses of such residues is to activate the enzyme active site by transferring their charge from one residue to other. In some of the experiments we can observe that the reactive group will be activated as in comparison with free Histidine or in contrast, the reaction rate constant with LDH is nearer to that for free histidine and indicates the loss of some unique active site property.

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