I just wanted to know why HLADH is classified as a dehydrogenase though it actually adds hydrogen to the reactant in an enzymatic reaction.
Hi there,
I guess you are talking about heart Lactate deshydrogenase (hLDH). The fact is that enzymes are potentially able to catalyze reversible reactions is both directions (and it is physiologically essential for the role of LDH in fact). So, about LDH, whether you consider reaction from lactate to pyruvate, it is about oxidization of lactate into pyruvate (deshydrogenase activity) or you consider the activity of reduction of pyruvate to lactate. An other striking example is pyruvate kinase which actually never works this way : in vivo, PK catalyzes PEP+ADP----> Pyruvate + ATP and this reaction is actually irreversible due to physiological condition.
Probably it is Horse Liver Alcohol Dehydrogenase. NAD+ is a cofactor in this enzyme and a hydride is abstracted from the substrate and added to the cofactor to make NADH. The enzyme can carry a reverse reaction which probably is what you are talking about.
February 10, 2016
Dear Tejkiran
Dr Liger wrote the answer. HLADH is a hear biomarker. Dehydrogenases (current names) act with their coenzymes, usually NAD(P) (or NAD(P)H, H+, and substrates. Their reactions are reversible. Thus, HLADH catalyzes the reduction of pyruvate (e, H acceptor) to lactate in the presence of NADH, H+ (e, H donor). Also, it catalyzes oxidation of lactate to pyruvate in the presence of NAD+. Both reactions are possible depending on physiological state or in vitro conditions. Alcohol dehydrogenase is a current example that you can consider.
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