Pyruvate Kinase/Lactic Dehydrogenase enzymes from rabbit muscle

Pyruvate Kinase from rabbit muscle is a metalloenzyme which catalyzes the conversion of phosphoenol pyruvate to pyruvate in the glycolysis pathway. It corresponds to a molecular weight of 59 kDa. It exists as a tetramer and undergoes conformational changes in the active site to accommodate substrate. Lactic dehydrogenase (LDH) catalyzes the lactate to pyruvate conversion in anaerobic glycolysis. It exists as tetramer and comprises of two subunits (H and M). The LDH of eukaryotes undergo active-site loop gating for their catalytic functionality.

Pyruvate Kinase/Lactic Dehydrogenase enzymes from rabbit muscle has been used:

• for ATP generation in the active microtubule preparation
• in the enzyme linked ATPase assay of skeletal muscle heavy meromyosin (HMM)
• as a standard control for quantifying mesenchymal stem cells (MSCs) lactate dehydrogenase

ADP Quantification Assay protocol for the use of PK/LDH in the determination of ADP. Solutions containing unkown concentrations of ADP can be substuted for reagent D in this protocol. Further dilutions of the ADP solution may be required

Lactate dehydrogenase from rabbit muscle can be inhibited by ascorbate. Aldolase and actin were shown to block this inhibitory effect.

Pyruvate kinase also catalyzes the phosphorylation of thiamine diphosphate (TDP) to thiamine triphosphate (TTP) which may find application in antiviral and tumor therapy.

Pyruvate kinase requires bivalent and monovalent cations such as Mg²⁺ and K⁺ respectively for activation to occur.

Pyruvate kinase activity: One unit will convert 1.0 μmole of phospho(enol)pyruvate to pyruvate per min at pH 7.6 at 37 °C.
Lactic dehydrogenase activity: One unit will reduce 1.0 μmole of pyruvate to L-lactate per min at pH 7.5 at 37 °C.

Solution in 50% glycerol containing 10 mM HEPES, pH 7.0, 100 mM KCl and 0.1 mM EDTA