Guanidinoacetic acid

The terminal amidino group of arginine is transferred intact to a number of other substances in simple displacement reactions. An example is the formation of guanidinoacetic acid (Eq. 24-27, steps a and b). 

Derivatives. Procedures are formulated for the preparation of S-methylisothiourea sulfate" and guanidinoacetic acid."... 

Creatine is synthesized in the kidneys, liver, and pancreas by two enzymatically mediated reactions. In the first, transami-dation of arginine and glycine forms guanidinoacetic acid in the second, methylation of guanidinoacetic acid occurs with S-adenosylmethionine as the methyl donor. Creatine is then transported in blood to other organs, such as muscle and brain, where it is phosphorylated to phosphocreatine, a high-energy compound. 

Van Pilsum JF, Martin RP, Kito E. Determination of creatine, creatinine, arginine, guanidinoacetic acid, guanidine and methyl-guanidine in biological fluids. 

In addition to arginine and glycine, AGAT has been shown to tolerate alternative compounds for both the donor and acceptor substrates. Amidino-donating substrates include arginine, guanidinoacetic acid, and canavanine, and acceptor substrates include glycine, ornithine, canaline, ethanolamine, 4-aminobutyric acid. 

Guanidinoacetic acid Phosphatid ylttlia noliimiHe DNA-adenine or - cytosine tRNA b ises NicotinamLde... 

Norepinephrine is methylated in the presence of a specific enzyme (S-adenosylmethionine transferase) and a cofactor (S-adenosylmethionine) to form epinephrine. This reaction is analogous to the methyla-tion of guanidinoacetic acid, which occurs in liver. Two distinct enzyme reactions are involved methionine is converted to S-adenosylmethionine in the presence of a methionine-activating enzyme and ATP, in which reaction all the phosphates of ATP are lost, the terminal phosphorus of ATP is liberated as inorganic phosphate and the two internal phosphoryl groups yield pyrophosphate and (2) norepinephrine is then methylated in the presence of a specific enzyme S-adenosylmethionine transferase to form epinephrine. 

Derivatives of guanidinoacetic acid (Formula 8.12) are among the sweetest compounds known until now (Table 8.8). 

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