Energy buffer

Creatine phosphate (also called phosphocreatine, PCr) is asmall compound which is a more energy rich (has a more negative AG° ) and is present in greater concentration ( 75 mmol/kg) than ATP and so is able to rephosphorylate ADP so acts as an energy buffer ... 

Phosphocreatine, derived from creatine, is an important energy buffer in skeletal muscle (see Fig. 13-5). Creatine is synthesized from glycine and arginine (Fig. 22-26) methionine, in the form of S-adenosylmethionine, acts as methyl group donor. 

Wind-powered The electrolyser current is controlled by the DC-DC step-down converter, while the current to the battery storage was not controlled, with the battery acting as an energy buffer, and the dump loads were controlled in order to limit the maximum voltage to the battery to prevent overcharging. 

The creatine synthesized in the liver is transported through the bloodstream to skeletal and heart muscle. It enters the mitochondria, where it is phosphorylated to crealine-P Creatine kinase catalyzes this reversible addition of a phosphate group, as shown in Figure 4.34. Creatine-P is unique in that its only known function is as an energy buffer. The creatine P formed in the mitochondria travels to the contractile proteins in the cytoplasm of the muscle fiber. The polymer, or complex, of contractile proteins is called a myofibril. Contraction of a myofibril is coupled to the hydrolysis of ATP to ADP. The immediate replenishment of ATP is catalyzed by a second creatine kinase, residing on the myofibril, that catalyzes the conversion of creatine-P to creatine. This reversal of the reaction takes place in the... 

FICURE 4.34 Ust of creatine as an energy buffer and degradation of Creatine phosphate. 

The scenario depicted in Figure 4.35, conversion of thecreatinc-P energy buffer, bound to myofibrils, to creatine and regeneration of creatine-P in the mitochondrion, is called the creatine phosphate shuttle. 

The on-line coupling between TLC and mass spectrometry provides a powerful combination for the detection and identification of substances separated by a planar chromatographic method. The on-line coupling between these two methods has to overcome the problem of vaporizing and introducing the sample into the mass spectrometer. Different methods are reported in the literature, but the analytical principle is the same the sample is ionized from the layer surface by means of a laser beam, under vacuum, and in the presence of an energy-buffering matrix. Once the ions are transferred into the mass spectrometer, more sophisticated methods can be applied for data analysis and interpretation, e.g., MS-MS. 

Glycine and arginine give rise to creatine and phosphocreatine, an energy buffer. Glutathione, formed from three amino acids, is an important cellular reducing agent. 

Creatine Cr has its major peak at 3.0ppm. It contains contributions mainly from Cr and its phosphorylated form phosphocreatine. An additional peak for Cr may be visible at 3.95 ppm. Therefore, the Cr peak is sometimes referred to as total Cr. Phosphocreatine has the role of an energy buffer in adenosine triphosphate (ATP) and adenosine diphosphate (ADP) reservoirs. ATP is a high-energy phosphate, which is used in all cells for energy-consuming tasks. 

Describe how creatine phosphate serves as a high-energy buffer in vertebrate muscle. 

Activation Energy Buffer 29.6 kcal Plasma 16.9 kcal... 

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