This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
LDH isoenzyme specific for heart is - 
Select and explain. 
A. LDH1, B. LDH2, C. LDH3, D. LDH4
A: LDH1
Answer: A: LDH1 
Explanation: Ans. is 'a' i.e., LDH1* Lactate Dehydrogenase converts pyruvate to lactate.* It is present in cytoplasm of cells* It is a tetramer. Two subunits H and M in various combinations make up the various isoenzymes of LDHLDH ISOENZYMESUBUNITSLOCATIONLDH 1H4Heart, RBC, BrainLDH 2H3M1Reticuloendothelial cellsLDH3H2M2LungsLDH4H1M3Kidneys, placenta, PancreasLDH 5M4Liver and skeletal muscle* In blood generally LDH 2 isoenzyme concentration is higher. In myocardial infarction, LDH1 concentration is increased. This LDH 1 being more than LDH2 is called as flipped pattern of LDH which is suggestive of myocardial infarction.