Abstract
We have previously reported a patient with anatomically-proved myocardial infarction in which no elevation of serum creatine kinase (CK) activity was demonstrated. Isoenzyme study revealed an absence of both CK-MB and CK-MM activity in the serum.
In this paper we determined immunoreactive CK-MM by the enzyme immunoassay in serum as well as tissues of caridiac, skeletal and rectal muscles of this patient to investigate whether the deficiency of MM isoenzyme activity is due to inhibition of activity or to deficiency of MM isoenzyme protein.
The amount of the CK-MM protein was markedly decreased in both serum and muscles, while enolase ft-subunit and S100ao, the specific marker antigens for the cardiac and skeletal muscles, were normally present. The complete absence of CK-MM protein in the serum and muscles were also confirmed by SDS-PAGE protein stain stain as well as immunoblotting.
Deficiency of the CK-MM protein appeared not to be fatal as seen in this patient. Compensation for the deficiency of CK-MM could be carried by CK-BB, mitochondrial CK or an alternate pathway of ATP production through adenylate kinase in the muscle tissues.
