Talk:Creatine kinase

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Creatine Kinase levels are also tested in children with inherited disorders of skeletal muscle such as dystrophies. I think one might want to add a section on this...

Myoglubin is an other word for Creatine Kinase , yes or no?? Who wants to give an answer? By Mfg

Reply to the above query: No, myoglobin is definitely not creatine kinase. The former is present on the surface (cell membrane) of skeletal muscle fibers (particularly, the "slow" fibers imparting a pinkish hue in the process) and helps "trap" oxygen for these fibers. This molecule is like hemoglobin in that it too contains the iron-containing heme group, but with this important difference that each molecule of the latter contains four molecules of heme instead of one (present in myoglobin). Hopefully, this should clear your doubt. --KC Panchal 21:55, 5 February 2007 (UTC)

[edit] Thermodynamic feasibility of conversion of creatine to phosphocreatine

I got this doubt reading the 25th edition Harper's Biochemistry (the latest is the 26th edition), which I couldn't get resolved even after searching on the Internet including Wikipedia. There is a mitochondrial creatine kinase (miCK) present between the inner & outer mitochondrial membranes, which phosphorylates creatine to phosphocreatine at the cost of an ATP molecule (ATP-->ADP), which is exported out the mitochondrion through the pore protein 'P' (pages 147-148). What is the need for such an enzyme if any way cytosolic creatine kinase can carry out the same reaction? My guess, is that it must be faster to transport phosphocreatine out of the mitochondrion than ATP, but I do not know for sure (as such a thing is not WRITTEN in the text); then, once in the cytosol, the phosphocreatine must be getting converted back to creatine, phosphorylating ADP to ATP in the process. But, an even bigger doubt is how id the reaction creatine-->phosphocreatine (requiring 43.1 kJ/mol) thermodynamically feasible if ATP-->ADP releases only 30.5 kJ/mol (page 126; table 12-1)? Looking forward to replies--answers/guesses/just about anything. KC Panchal 11:57, 5 February 2007 (UTC)