Thrombin and adenosine diphosphate (ADP) supported the binding of 125l-fibrinogen to washed human platelets with similar kinetics and affinity. Platelet secretion, as measured by 14C-serotonin release, and fibrinogen binding exhibited an identical dependence on thrombin concentration. Enzymatic removal of ADP with apyrase or creatine phosphate/creatine phosphokinase (CP/CPK) from thrombin-stimu...

Direct assay of creatine kinase by the method of Siegel and Cohen with the Technicon “SMA 12/60” is compared with two indirect coupled-enzyme assay methods. The direct method was linear to greater than 2000 U/liter, whereas the indirect methods were linear to 250 and 1500 U/liter, with use of serial dilutions of a creatine kinase preparation. Increasing the activity of the auxiliary enzymes, he...

A computer technique for determination of the distribution of adenine nucleotides among compartmented, protonated, and metal-chelated species has been developed for the perfused rat heart. This procedure requires knowledge of tissue levels of creatine, creatine phosphate, ATP, ADP, and AMP and the glycolytic and respiration rates. The method is applicable to any physiological state of the organ...

We have introduced a single knock-out mutation in the mitochondrial creatine kinase gene (ScCKmit) in the mouse germ line via targeted mutagenesis in mouse embryonic stem (ES) cells. Surprisingly, ScCKmit -/- muscles, unlike muscles of mice with a deficiency of cytosolic M-type creatine kinase (M-CK -/-; Van Deursen et al. (1993) Cell 74, 621-631), display no altered morphology, performance or ...

Defining how extramitochondrial high-energy phosphate acceptors influence the rates of heart oxidative phosphorylation is essential for understanding the control of myocardial respiration. When the production of phosphocreatine is coupled to electron transport via mitochondrial creatine kinase, the net reaction can be expressed by the balanced equation: creatine + Pi----phosphocreatine + H2O. T...

We investigated the effects of chronic creatine loading and voluntary running (Run) on muscle fiber types, proteins that regulate intracellular Ca2+, and the metabolic profile in rat plantaris muscle to ascertain the bases for our previous observations that creatine loading results in a higher proportion of myosin heavy chain (MHC) IIb, without corresponding changes in contractile properties. F...

L-Arginine-:glycine amidinotransferase (EC 2.1.4.1) catalyzes the transfer of an amidino group from arginine to glycine to form guanidinoacetate, precursor in creatine synthesis. The kidneys are major site of the creatine synthesis and primary target organs for mercury toxicity. In evaluation of molecular mechanisms of mercury chloride intoxication relating to creatine metabolism we have invest...