Lactate dehydrogenase (LDH) is present in a wide variety of organisms, including plants and animals. It is an oxidoreductase which catalyses the interconversion of pyruvate and lactate with concomitant interconversion of NADH and NAD+. As it can also catalyze the oxidation of hydroxybutyrate, it is occasionally called Hydroxybutyrate Dehydrogenase (HBD). There are 5 different isoenzymes of LDH, LDH1 to LDH5, each composed of 4 subunits which may be of 2 different types-M and H subunits. These subunits are encoded by two different genes: The M subunit is encoded by gene LDHA whilst the H subunit is encoded by LDHB. Usually LDH2 is the predominant form in the serum. An LDH1 level higher than the LDH2 level suggests myocardial infarction (damage to heart tissues releases heart LDH, which is rich in LDH1, into the bloodstream).
Lactate Dehydrogenase Isoenzyme 3 (LDH3) from human erythrocytes (red blood cells).
Activity: ~1000 Units/ml @37ºCnProtein: ~2mg Protein/ml (Commassie)Specific Activity: ~200 Units/mg ProteinUnit Definition:One unit will catalyze the transformation of one micromole of L-lactate to pyruvate/minute at 37°C and pH 8.55.
Storage and Stability:May be stored at 4°C. For long-term storage, aliquot and store at 4°C. Do not freeze. Aliquots are stable for 6 months. For maximum recovery of product, centrifuge the original vial prior to removing the cap. Further dilutions can be made in assay buffer.
