On agarose gel electrophoresis of lactate dehydrogenase isoenzymes, which fraction migrates most slowly toward the anode and predominates in liver disease?
- A LDH1
- B LDH5 ✓
- C LDH3
- D LDH2
Correct answer: B. LDH5
Explanation
LDH is a tetramer of H and M subunits. LDH1 (H4) carries the greatest negative charge and migrates fastest toward the anode, while LDH5 (M4) is least charged and migrates slowest. Liver contains predominantly M subunits, so LDH5 is the major isoenzyme released in hepatocellular injury and in shock liver. Cardiac muscle is rich in H subunits, giving the LDH1 predominance responsible for the flipped LDH1 greater than LDH2 pattern of myocardial infarction.
Reference: Harper's Illustrated Biochemistry, 31st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.