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Creatine phosphate formation

Under standard conditions, this reaction would be unfavourable but physiological conditions during recovery phase after exercise are such as to allow creatine phosphate formation to occur. [Pg.247]

In resting muscle the high concentration of ADP does not decrease the proton gradient effectively and the high membrane potential slows electron transport. ADP, formed when ATP is hydrolyzed by myosin ATPase during contraction, may stimulate electron transport. However, the concentration of ATP (largely as its Mg salt) is buffered by its readily reversible formation from creatine phosphate catalyzed in the intermembrane space, and in other cell compartments, by the various isoenzymes of creatine kinase (reviewed by Walliman et al., 1992). [Pg.136]

The enzyme creatine kinase (CK) facilitates the transfer of phosphate and energy to a molecule of ADP to form ATP. Stores of creatine phosphate are sufficient to sustain approximately 15 more seconds of muscle contraction. Because this is a single-step process, it provides ATP very rapidly and is the first pathway for formation of ATP to be accessed. [Pg.146]

Muscle-specific auxiliary reactions for ATP synthesis exist in order to provide additional ATP in case of emergency. Creatine phosphate (see B) acts as a buffer for the ATP level. Another ATP-supplying reaction is catalyzed by adenylate kinase [1] (see also p.72). This disproportionates two molecules of ADP into ATP and AMP. The AMP is deaminated into IMP in a subsequent reaction [2] in order to shift the balance of the reversible reaction [1 ] in the direction of ATP formation. [Pg.336]

In the standard state, the equilibrium for this reaction lies far to the left in other words, the reaction is unfavored. However, in the standard state, all the reactants and products are at one molar concentration. In other words, the ratio of ATP to ADP concentrations would be 1. In an actively metabolizing state, the ratio of ATP to ADP is as much as 50 or 100 to 1—this means that the formation of Cr P will occur to a reasonable level. Creatine phosphate forms a reservoir for high-energy phosphate in the same way that water can be pumped upstream to a reservoir and released for use later on. [Pg.120]

Both creatine and creatine phosphate undergo a nonenzymic reaction to yield creatinine, which is metaboUcaUy useless and is excreted in the urine. Because the formation of creatinine is a nonenzymic reaction, the rate at which it is formed, and the amount excreted each day, depends mainly on muscle mass, and is therefore relatively constant from day to day in any one individual. This is commonly exploited in clinical chemistry urinary metabolites are commonly expressedper mole of creatinine, and the excretion of creatinine is measured to assess the completeness of a 24-hour urine collection. There is normally Utffe or no excretion of creatine in urine significant amounts are only excreted when there is breakdown of muscle tissue. [Pg.393]

Adenosine triphosphate creatine A-phosphotransferase (EC 2.7.3.2), also creatine phosphokinase. Creatine kinase is found in muscle and is responsible for the formation of creatine phosphate from creatine and adenosine triphosphate creatine phosphate is a higher energy source for muscle contraction. Creatine kinase is elevated in all forms of muscular dystrophy. Creatine kinase is dimer and is present as isozymes (CK-1, BB CK-2, MB CK-3, MM) and Ck-mt (mitochondrial). Creatine kinase is also used to measure cardiac muscle damage in myocardial infarction. See Bais, R. and Edwards, J.B., Creatine kinase, CRC Crit. Rev. Clin. Lab. ScL 16, 291-355, 1982 McLeish, M.J. and Kenyon, G.L., Relating structure to mechanism in creatine kinase, Crit. Rev. Biochem. Mol. Biol 40, 1-20, 2005. [Pg.84]

Creatine synthesis. The synthesis of creatine, including the major control, is depicted above. The tissue where the reaction occurs is indicated in parenthesis in purple. The formation of creatinine from creatine phosphate is also shown. (See text for more detail.)... [Pg.510]

Creatine phosphokinase. The formation of creatine phosphate and its use to reform ATP is shown above. [Pg.511]

The positive value of AG shows that the reaction will not proceed toward the net formation of ATP, so that under these conditions, creatine phosphate does not serve as a donor of phosphoryl groups to ATP. Instead, the reaction proceeds toward the net formation of creatine phosphate, with phosphoryl groups donated from ATP. [Pg.240]

FIGURE 20.7 Formation of creatine phosphate, creatinine phosphate, and creatinine. [Pg.671]

Fig. 3. The effect of eRF on ternary complex formation. (A) The assay for ternary complex formation was performed according to Gupta et al. (12). A typical reaction mixture of 25 /nl contained 20 mM HEPES-KOH, pH 7.6,120 mM KAc, 2 mM MgAc, 1 mM ATP, 0.4 mM GTP, 5 mM creatine phosphate, 0.05 unit of creatine kinase, 1 mM dithiothreitol, 5 pmole PH]Met-tRNA, and 1.5 pmole eIF-2 and eRF as indicated. Incubation was for 10 minutes at 37°C. The reaction was stopped by adding buffer with 0 mM Mg, followed by filtration through cellulose-nitrate filters. The filters were washed twice, dried, and counted. (B) Temaiy complex formation with 2.5 pmole eIF-2 (O) or 3 pmole eIF-2 eRF ( ). The filters were washed with 0 mM Mg because the ternary complex is most stable at this Mg concentration. Fig. 3. The effect of eRF on ternary complex formation. (A) The assay for ternary complex formation was performed according to Gupta et al. (12). A typical reaction mixture of 25 /nl contained 20 mM HEPES-KOH, pH 7.6,120 mM KAc, 2 mM MgAc, 1 mM ATP, 0.4 mM GTP, 5 mM creatine phosphate, 0.05 unit of creatine kinase, 1 mM dithiothreitol, 5 pmole PH]Met-tRNA, and 1.5 pmole eIF-2 and eRF as indicated. Incubation was for 10 minutes at 37°C. The reaction was stopped by adding buffer with 0 mM Mg, followed by filtration through cellulose-nitrate filters. The filters were washed twice, dried, and counted. (B) Temaiy complex formation with 2.5 pmole eIF-2 (O) or 3 pmole eIF-2 eRF ( ). The filters were washed with 0 mM Mg because the ternary complex is most stable at this Mg concentration.
The basis of this relationship is that urinary creatinine is the only degradation product of creatine phosphate [338] that cardiac and skeletal muscle contribute more than 90% of body creatine [346] and that creatine phosphate to creatinine degradation occurs at a fixed rate (non-enzymatically) [347]. Thus normally, the rates of formation and excretion of urinary creatinine would depend on the size and turnover rate of the creatine pool, and the relationship between muscle mass and creatine excretion would depend primarily on muscle creatine content. [Pg.62]

ATP formation on creatine and MgCl2 concentrations was also examined and the results are summarized in Fig. 6 and Fig. 7. Without creatine, ATP formation occurred later and more slowly but at the same high conversion level. The addition of excess creatine caused acceleration of ATP formation. Without creatine, the induction period took two times longer. As shown in the time conversion curve with heptakis-(2,6-dimethyl)-g-CD (DM-g-CD) without creatine, ATP formation occurred later and more slowly at the same conversion level. Besides these examinations, the effect of O2, buffer solution and temperature were observed. Without O2, the reaction did not proceed. Ionic strength and pH of the phosphate buffer and reaction temperature were optimum under the present conditions. The results obtained here showed the same kind of catalytic activity of the CD in the equilibrium between ADP and ATP in this scheme 1. This new type of transphosphorylation seems to be a... [Pg.687]

Contact sites were first described by Hacken-BROCK (1968) in thin sections of liver mitochondria as places where the inner and outer mitochondrial membranes were in very close apposition. Van Ve-NETiE and Verkleij (1982) and Knoll and Brdiczka (1983) characterized them in freeze-fractured mitochondria. Knoll and Brdiczka (1983) and Brdiczka et al. (1986) postulated that contact sites play an important role in the regulation of the mirochondrial metabolism. Under nor-moxic conditions, the ATP formed in the mitochondria is converted into creatine phosphate by the activity of the translocase, and the mitochondrial isoenzyme of creatine kinase (Wallimann et al. 1992). So, if the cardiac metabolism is stimulated the mitochondrial ATP formation increases, as does the mitochondrial creatine kinase. Since mitochondrial creatine kinase is active in mitochondrial contact sites (Biermans et al. 1990, Nicolay et al. 1990, Jacob et al. 1992), and can even induce contact site formation (Rojo et al. 1991), the surface density of mitochondrial contact sites in this situation will be high. Mitochondria lose the ability to form contact sites after more than 15 min of ischaemia and this might be a first indication of irreversible injury (Barker et al. 1995). [Pg.582]

Such ATP synthesis is carried out in anaerobic conditions and is based on the transfer of phosphate residues onto ATP via the metabolite. For example ATP formation from creatine phosphate is accompanied by the transition of its NH group at ADP to NH group of creatine at ATP. [Pg.328]

The net result of ATP degradation and resynthesis will be the formation of creatine (Cr) and inorganic phosphate (Pj) and a decrease in phosphocreatine (PCr). [Pg.243]


See other pages where Creatine phosphate formation is mentioned: [Pg.161]    [Pg.161]    [Pg.826]    [Pg.210]    [Pg.215]    [Pg.380]    [Pg.383]    [Pg.384]    [Pg.384]    [Pg.570]    [Pg.826]    [Pg.327]    [Pg.82]    [Pg.509]    [Pg.192]    [Pg.92]    [Pg.671]    [Pg.137]    [Pg.144]    [Pg.348]    [Pg.135]    [Pg.59]    [Pg.30]    [Pg.170]    [Pg.481]    [Pg.36]    [Pg.211]   
See also in sourсe #XX -- [ Pg.384 ]




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