Chemical Properties
Off-white salt-free lyophilized powder, soluble in water, optimal pH 6.0-7.0 (positive reaction), 9.0 (negative reaction). Stability: inactivated at pH less than 5, thawing and freezing also inactivate the enzyme; -20℃, pH 6.6, in 0.1mot/L imidazole buffer can be stabilized for 4 weeks, neutral 60% ethanol solution is the most stable, dilute solution by adding 0.1% albumin or β-mercaptoethanol can increase the stability; freeze-dried products can be stored at -20℃ for 12 months, at 4℃ for 6 months. The freeze-dried product can be stored at -20℃ for 12 months, and at 4℃ for 6 months, it loses 15% of its vitality. Inhibitors include p-chloromercuric acid benzoic acid, chelating agent, iodoacetic acid, tripolyphosphoric acid, adenosine, nitrite, sulfate, bromide, sulfite, chloride, fluoride thyroxine, 3,5-dinitro-o-cresol, coenzyme I (NAD), L-triiodocarbonylammonium (T3), malonate, iodine (I-), iodoacetic acid, orthophosphate, pyrophosphate, and triple phosphoric acid, etc., and activators include Mg2+, Mn2+, 2-mercaptoethanol, dithiothreitol, glutathione, thiol N-acetylcysteine, etc. Absorbance coefficient of 1% aqueous solution at 280 nm was 8.76. Enzymatic reaction: creatine + adenosine triphosphate ═adenosine diphosphate + phosphocreatine.
Uses
The product has been used for tATPase assay of myofibrillar protein isolated from rabbit. This assay evaluated the kinetic influence of bound creatine kinase (CK) on Ca
2+-activated myosin ATPase. The product has also been used for the enzymatic hydrolysis of protein samples during tryptophan estimation by pyrolysis gas chromatography.
Biochem/physiol Actions
Creatine kinase plays a key role in the energy metabolism of cells with intermittently high and fluctuating energy requirements. Examples of such cells include cardiac or skeletal muscle cells and neural tissues of brain and retina. The enzyme catalyzes the reversible transfer of the phosphoryl group from phosphorylcreatine to ADP, in order to generate ATP. The molecular mass of the protein is found to be approximately 80,000 Da. It is made up of 2 subunits, each having a molecular weight of 40,000 ± 2000. The lighter subunit is present in larger amounts.
