Creatine kinase (CK) is widely distributed and seems to be primarily concerned with ATP regeneration. CK may represent 10-20% of muscle cytoplasmic protein. Protein: 0.6mg protein/mg (Coomassie) Activity: 250 U/mg protein (Dimension Clinical Chemistry System) Specific Activity: 200U/mg protein Unit Definition: One Unit will transfer one micromole of phosphate from Creatine Phosphate to ADP per minute at 37C. Measured at 340nm as one equimolar amount of NADH produced by a coupled reaction. Reconstitution: 1mg protein/ml in Tris buffered saline, pH 8.0 containing 1mM dithiothreitol and 1mM EDTA. Add glycerol to 50% (v/v) and store at -20C. Further dilutions should be in the reconstitution buffer plus 1% BSA as a carrier. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months after receipt at -20C. Reconstitute and aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. Store dessicated.
