Glycocyamine

Glycocyamine (or guanidinoacetate) is a metabolite of glycine in which the amino group has been converted into a guanidine by guanylation (transfer of a guanidine group from arginine). In vertebrate organism it is then transformed into creatine by methylation.

Glycocyamine is used as a supplement and as a feed additive in poultry farming. However, the metabolism of creatine from glycocyamine in the liver causes a depletion of methyl groups. This causes homocysteine levels to rise, which has been shown to produce cardiovascular and skeletal problems.^{[citation needed]} Glycocyamine plays a role in the metabolism of the amino acids serine, threonine, and proline.

Glycocyamine is formed in the mammalian organism primarily in the kidneys by transferring the guanidine group of L-arginine by the enzyme L-Arg:Gly-amidinotransferase (AGAT) to the amino acid glycine. From L-arginine, ornithine is thus produced, which is metabolized in the urea cycle by carbamoylation to citrulline.

In a further step, glycocyamine is methylated to creatine with S-adenosyl methionine by the enzyme guanidinoacetate N-methyltransferase (GAMT). The creatine is released into the bloodstream.

Guanidinoacetic acid was first prepared in 1861 by Adolph Strecker by reaction of cyanamide with glycine in aqueous solution:

Glycine can also be converted to glycocyamine with S-methylisothiourea or with O-alkylisoureas as a guanylation agent.

The recent patent literature describes the synthesis of glycocyamine by catalytic oxidation of ethanolamine to glycine and subsequent reaction with cyanamide in aqueous solution in high yield, analogous to the synthesis of creatine starting from 2-methylaminoethanol via sarcosine.

This synthetic route suppresses the formation of toxic dihydrotriazine and other undesired by-products (such as iminodiacetic acid).