| First Author | Saupe KW | Year | 2000 |
| Journal | J Biol Chem | Volume | 275 |
| Issue | 26 | Pages | 19742-6 |
| PubMed ID | 10867023 | Mgi Jnum | J:63069 |
| Mgi Id | MGI:1860391 | Doi | 10.1074/jbc.M001932200 |
| Citation | Saupe KW, et al. (2000) Kinetic, thermodynamic, and developmental consequences of deleting creatine kinase isoenzymes from the heart. Reaction kinetics of the creatine kinase isoenzymes in the intact heart. J Biol Chem 275(26):19742-6 |
| abstractText | Creatine kinase (CK) exists as a family of isoenzymes in excitable tissue. We studied isolated perfused hearts from mice lacking genes for either the main muscle isoform of CK (M-CK) or both M-CK and the main mitochondrial isoform (Mt-CK) to determine 1) the biological significance of CK isoenzyme shifts, 2) the necessity of maintaining a high CK reaction rate, and 3) the role of CK isoenzymes in establishing the thermodynamics of ATP hydrolysis. (31)P NMR was used to measure [ATP], [PCr], [P(i)], [ADP], pH, as well as the unidirectional reaction rate of PCr--> [gamma-P]ATP. Developmental changes in the main fetal isoform of CK (BB-CK) were unaffected by loss of other CK isoenzymes. In hearts lacking both M- and Mt-CK, the rate of ATP synthesis from PCr was only 9% of the rate of ATP synthesis from oxidative phosphorylation demonstrating a lack of any high energy phosphate shuttle. We also found that the intrinsic activities of the BB-CK and the MM-CK isoenzymes were equivalent. Finally, combined loss of M- and Mt-CK (but not loss of only M-CK) prevented the amount of free energy released from ATP hydrolysis from increasing when pyruvate was provided as a substrate for oxidative phosphorylation. |
