Phosphagen

Harris, R.C., Sahlin, K., Hultman. E. (1977). Phosphagen and lactate contents of m. quadriceps femoris of man after exercise. J. Appl. Physiol. 43. 852-857. 

Figure 31-3. Arginine, ornithine, and proline metabolism. Reactions with solid arrows all occur in mammalian tissues. Putrescine and spermine synthesis occurs in both mammals and bacteria. Arginine phosphate of invertebrate muscle functions as a phosphagen analogous to creatine phosphate of mammalian muscle (see Figure 31-6).

Suzuki, T. Nishimura, Y. Umekawa, M. Yamamoto, Y Kawamichi, H. Furukohri, T. Evolution of phosphagen kinase VII. Isolation of glycocyamine kinase from the polychaete Neanthes diversicolor and the cDNA-derived amino acid sequences of a and chains. J. Protein Chem., 18, 13-19 (1999)... 

Moreland, B. Watts, D.C. Phosphagen kinases and evolution in the echino-dermata. Nature, 214, 458-462 (1967)... 

Storey, K.B. Purification and characterization of arginine kinase from the mantle muscle of the squid, Symplectoteuthis oualaniensis. Role of the phosphagen/phosphagen kinase system in a highly aerobic muscle. Arch. Biochem. Biophys., 179, 518-526 (1977)... 

S.J. Ellington, W.R. Chapman, M.S. Expression, purification from inclusion bodies, and crystal characterization of a transition state analog complex of arginine kinase a model for studying phosphagen kinases. Protein Sci., 6, 444-449 (1997)... 

Platzer, E.G. Wang, W. Thompson, S.N. Borchardt, D.B. Arginine kinase and phosphoarginine, a functional phosphagen, in the rhabditoid nematode Steinernema carpocapsae. J. ParasitoL, 85, 603-607 (1999)... 

Suzuki, T. Kawasaki, Y Furukohri, T. Evolution of phosphagen kinase. Isolation, characterization and cDNA-derived amino acid sequence of two-domain arginine kinase from the sea anemone Anthopleura japonicus. Biochem. J., 328 (Pt 1), 301-306 (1997)... 

S Additional information <1> (<1> no phosphorylation of arginine, guani-dinoacetate, no reverse reaction with their corresponding phosphagens... 

Piccinni, E. Coppellotti, O. Phosphagens in protozoa - II. Presence of phosphagen kinase in Ochromonas danica. Comp. Biochem. Physiol. B, 62, 287-289 (1979)... 

When a sudden demand for energy depletes ATP, the PCr reservoir is used to replenish ATP at a rate considerably faster than ATP can be synthesized by catabolic pathways. When the demand for energy slackens, ATP produced by catabolism is used to replenish the PCr reservoir by reversal of the creatine kinase reaction. Organisms in the lower phyla employ other PCr-like molecules (collectively called phosphagens) as phosphoryl reservoirs. 

ATP provides the immediate source of energy for muscles but its concentration is only -5 mM. As discussed in Chapter 6, Section D, phosphagens, such as creatine phosphate, are also present and may... 

The most dramatic illustration of a mass-specific illusion is the comparative heat dissipation of the human erythrocyte and platelet. In mammals, both of these cell types are anucleate and discoid in shape, but the longest dimension of the former is four times that of the latter. Yet heat production of a human erythrocyte was shown to be 10 fW, a sixth that of a human platelet (61 fW see Table 1). The relatively high metabolic activity of platelets is probably due to the need to maintain a considerable phosphagen (phosphocreatine) pool for actomyosin contraction at stimulation and clot retraction. Phosphocreatine is synthesized from creatine using ATP and acts as a demand on the ATP cycle to drive the coupled catabolic half-cycle. On the other hand, ATP requirements of the erythrocyte are relatively small, being mostly confined to active transport of ions at the plasma membrane. 

Muscle and other tissues from both vertebrates and invertebrates usually contain a reserve of high-energy phosphate in the form of phosphagens. The phosphagens are all guanidines and they react reversibly with ATP ... 

The major phosphagens found in nature are arginine and creatine but parasitic helminths are unusual in that they possess no detectable phosphagens and none occurs in Hymenolepis diminuta, Moniezia expansa, Ligula intestinalis or Schistocephalus solidus (44). This absence of phosphagens has implications for control of metabolism in cestodes. If... 

Barrett, J. Lloyd, G. M. (1981). A novel phosphagen phosphotransferase in the plerocercoids of Schistocephalus solidus (Cestoda Pseudophyllidea). Parasitology, 82 11-16. 

The simplest mechanism for generating ATP is phosphagen mobilization. In vertebrate tissues such as muscle containing creatine phosphate (PCr) this mobilization is catalyzed by creatine phosphokinase (CPK), a process which requires no 02 and can be written as follows ... 

Other phosphagens (such as arginine phosphate, lombrocine phosphate, tauromyocine phosphate) are found in many invertebrate muscles. 

It is therefore reasonable to suppose that the phosphagens, as distinct from inorganic PolyPs, arose in the course of evolution subsequent to ATP. The function of detoxification of orthophosphate has in most cases, however, evidently ceased to be necessary as a result of evolutionary development in the higher organisms of a very delicately balanced metabolism and of mechanisms for its precise control. In many cases, the need of elimination of Pi surplus in a form, which is non-toxic to the cell, has again appeared in certain tissues of the higher organisms. 

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