Indices for the age of the creatine kinase M-chain in the blood

Abstract

SummaryThe apparent activation energy of the CK reaction as well as the Michaelis-Menten constants and the isoelectric point of CK MM can be used as indices for the mean age of the CK M-chain in the blood in vivo and in vitro. Modifications in the CK M-chain take place in vivo in the blood and in vitro in a serum matrix. Gradual increases in the apparent activation energy are also observed both in vivo and in vitro. It is confirmed that the modification in the CK M-chain causes a rise in the apparent activation energy, u.A gradual increase in apparent activation energy, due to the ageing process of the CK M-chain, was observed after myocardial infarction. A significantly increased value for u was observed at the time that total CK activity already had returned to reference values. In spite of the normal CK value, the apparent activation energy still indicated that there had been myocardial damage. The Michaelis-Menten constants for creatine phosphate and ADP are also influenced significantly by the modification in the M-chain. While the apparent activation energy increases, the Michaelis constants decrease in the order MM,, MM,, MM,. The Michaelis-Menten constants for both ADP and CrP can be used as an index for the mean age of the enzyme in the blood.The Michaelis-Menten constants for CrP and ADP show significant variations with the measuring temperature for virtually all CK MM forms.

Kinetic Characterization of Human Heart and Skeletal Muscle CK Isoenzymes

“…Szasz and Gruber [11] have reported marked differences in ap parent Km values between purified and na tive CK MM isoenzyme in human serum. Further, a recent report by Wevers et al [21 ] showed that Km values are influenced by modification of the M chain during the posttranslational aging process.…”

lFCC Section

“…The proposed method for the measurement of the catalytic concentration of creatine kinase in serum is based on the principles proposed by Oliver (27) and later modified by Rosalki (28) and by Szasz, Gerhardt 'and co-wprkers in a series of publications (23, 29^· 34). Recommended or Standard methods published by Professional societies in the United Kingdom (35), Federal Republic of Germany (36), the Netherlands (37), France (38), Scandinavia (39,40), and Switzerland (41) are also based on these publications and have also been considered.…”

“…28) estimate the effec ve equilibrium concentrations of Mg-ADP and creatine phosphate to be 1,61 mmol/1 and 25,8 mmol/1, respectively, at the nominal reaction conditions.…”

International Federation of Clinical Chemistry (IFCC): Scientific Division, Committee on Enzymes. IFCC methods for the measurement of catalytic concentration of enzymes. Part 7. IFCC method for creatine kinase (ATP: creatine (N‐phosphotransferase, EC 2.7.3.2). IFCC Recommendation

“…Because the nucleotide binds to the active site as the magnesium ion complex, magnesium ion concentration is important in establishing the equilibrium concentration ofcomplexed nucleotide. Wevers et al [28] estimated that the effective equilibrium concentrations of Mg-ADP and creatine phosphate were 1. '61 mmol/1 and 25"8 mmol/1, respectively, at the nominal reaction conditions.…”