Pyruvate Kinase from rabbit muscle

Research Area: Cell Signaling

Pyruvate kinase from rabbit muscle catalyzes ATP-dependent phosphorylation of glycolate to yield 2-phosphoglycolate.Pyruvate kinase, an enzyme, is found in a tetrameric or a dimeric form. PKM1, PKM2, PKR, and PKL are the four mammalian pyruvate kinase isoforms.

Pyruvate kinase from rabbit muscle has been used in:

• a structural study to understand the reaction mechanism of the final step in glycolysis.
• a study to investigate ATP-dependent phosphorylation of α-substituted carboxylic acids.
• enzyme assays.

Molecular Weight: 237 kDa and exists as a tetramer of four equal subunits of molecular weight 57 kDa.
Isoelectric Point: 7.6
Optimal pH: ∼7.5
Optimal Temperature: 25°C
ΕA₂₈₀ = 0.54 for 1 mg(p)/ml, 1 cm path
Reported K_M values are ATP (0.86 mM), pyruvate (10 mM), ADP (0.3 mM), and PEP (0.07 mM) in Tris buffer at pH 7.4 and 30 °C. Pyruvate kinase is highly specific for phosphoenolpyruvate, but can utilize other dinucleotide triphosphates as substrates in place of ATP including GTP, ITP, dATP, UTP, and CTP.

Pyruvate kinase from rabbit muscle can be activated by histidine and inhibited by low levels of zinc (Zn²⁺). In the glycolytic pathway, pyruvate kinase (PK) functions as a terminal enzyme, catalyzing the conversion of phosphoenolpyruvate to pyruvate and the synthesis of ATP through substrate-level phosphorylation. Tetrameric structures of PK are more active and have a high affinity for phosphoenolpyruvate (PEP), whereas dimeric structures are less active and have a low affinity for PEP. PK from rabbit muscle possesses positive kinetic cooperativity (Hill coefficient> 1.35) of the phosphoenol pyruvate and adenosine diphosphate(ADP) binding sites.

One unit will convert 1.0 μmole of phospho(enol)pyruvate to pyruvate per min at pH 7.6 at 37 °C.

Suspension in 3.2 M (NH₄)₂SO₄ solution, pH 6

Protein determined by biuret.