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Creatine Phosphokinase from rabbit muscle

Type I, salt-free, lyophilized powder, ≥150 units/mg protein

Creatine Kinase, Phosphocreatine phosphokinase, ATP: Creatine N-Phosphotransferase, CPK
CAS Number:
Enzyme Commission number:
EC Number:
MDL number:

Quality Level


Type I


salt-free, lyophilized powder

specific activity

≥150 units/mg protein

mol wt

80-86.2 kDa


0.25 M glycyl-glycine, pH 7.4: soluble 5.0 mg/mL, clear, colorless to slightly yellow

foreign activity

ATPase ≤0.01%
Lactic dehydrogenase, hexokinase, myokinase and pyruvate kinase ≤0.001%

shipped in

wet ice

storage temp.


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The enzyme from Sigma has been used in the measurement of phosphocreatine in hippocampal neurons isolated from rat brains.
Molecular Weight: ~81,000
Creatine Phosphokinase is a dimer composed predominantly of the skeletal muscle derived homodimer (MM). CK also exists as a heterodimer (MB) particularly in the myocardium. CK derived from brain tissue consists mainly of the brain source homodimer (BB). The amino acid sequences of the M chain and B chains are about 80% homologous. From the sequence, the molecular weight of the M chain is 43,112.

E1%(280)= 8.76

pH Optimum: pH 8.8-9.0 for the forward reaction and pH 6.0-7.0 for the reverse reaction.

CK is a cellular enzyme with a wide tissue distribution. Its physiological role is associated with ATP generation for contractile or transport systems. Increased levels of CK are associated with myocardial infarction, muscular dystrophy, hyperthyroidism, pulmonary infarction and cerebrovascular disease. Variations in relative isozyme distribution can provide additional information in the diagnosis of these conditions.

Substrates: Creatine, N-ethylglycocyamine and glyocyamine have been shown to act as substrates for CK. CK is very specific for ATP/ADP.

Inhibitors: ADP is a strong inhibitor of the forward reaction competing with ATP. Divalent cations such as Ca2+ (Ki=4.5 mM), Zn2+ and Cu2+ inhibit CK by competing with Mg2+. Other inhibitors include acetate, acetylsalicylic acid, adenosine, p-aminosalicylic acid, AMP, benzoic acid, bicarbonate, bromide, chloride, p-Chloromercuribenzoic acid, ethylene oxide, 2,4-fluorodinitrobenzene, iodide, malonic acid, NAD, nitrate, phosphate, pyrophosphate, salicylic acid, sulfate, sulfite, thyroxine, trichloroacetate, L-triiodothyroxine, L-triiodothyronine, and tripolyphosphate.


500, 1000, 3500, 17500, 35000 units in poly bottle


The use of 0.1% albumin in the reaction buffer is recommended to avoid inactivation due to dilution.

Unit Definition

One unit will transfer 1.0 μmole of phosphate from phosphocreatine to ADP per min at pH 7.4 at 30 °C.

Preparation Note

Produces a clear, colorless to light yellow solution at 5 mg/mL in 0.25 M glycyl-glycine, pH 7.4

Analysis Note

Protein determined by biuret.

Storage Class Code

13 - Non Combustible Solids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificate of Analysis

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Certificate of Origin

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