Pyruvate Kinase (PK)

ATP:pyruvate 2-O-phosphotransferase
Pyruvate kinase has a molar mass of 237,000 and exists as a tetramer. Each polypeptide chain of this tetramer has a molar mass of 57,200. The enzyme contains two identical catalytic particles called protomers. Each of these protomers contains two polypeptide chains. Each protomer contains one site each for Mn²⁺ and phosphoenolpyruvate.[1]

Pyruvate kinase has been used to measure ATPase activity[2] and in the determination of adenylate concentration.[3]

Pyruvate kinase catalyzes the irreversible conversion of P-enolpyruvate and ADP to pyruvate and ATP with the utilization of a proton. The first step is the transfer of phosphate group from P-enolpyruvate to ADP with the formation of bound enolate of pyruvate and ATP. In the second step, a proton is added to enolate to generate the keto form of pyruvate. Apart from this, the enzyme exhibits other activities, such as ATP- and bicarbonate-dependent ATPase, phosphorylation of fluoride and hydroxylamine, ATP-dependent phosphorylation of glycolate, and decarboxylation of oxaloacetate.[4]

Suspension in 3.2 M ammonium sulfate solution, pH approximately 6

Activator: PK requires Mg²⁺ (or Mn²⁺, Co²⁺) and K⁺ (or NH⁴⁺, Rb⁺) for full activity.

Contaminants: <0.001% GK, <0.002% “NADH oxidase”, and ATPase, each, <0.01% enolase, LDH, and myokinase, each

For life science research only. Not for use in diagnostic procedures.