Perinatal enhancement of cardiac myofibrillar creatine kinase activity without change in enzyme Km
Dowell, R.T.; Fu, M.C.
American Journal of Physiology 265(2 Pt 1): C375-C378
1993
ISSN/ISBN: 0002-9513 PMID: 8368267 Document Number: 409761
Myofibrillar creatine kinase (CK) serves as one microcompartment of the phosphorylcreatine shuttle by providing ATP as substrate for adenosine-triphosphatase (ATPase). During perinatal heart development, augmentations of myofibrillar ATPase and CK occur in concert with increased contractile performance. The maximal reaction velocity (V-max) for CK doubles during development in both intact native myofibril and enzyme extracted from myofibril. The absence of alterations in ADP and creatine phosphate substrate Michaelis constants (K-m), isoenzyme composition, or total number of -SH groups suggests active site function (V-max) is influenced indirectly via a subunit domain effect on enzyme conformation.