[Relations between the phosphorylation of aminated molecules and their action on the absorption of calcium]

Various amino acids and guanidines (L-lysine, L-aspartic and L-glutamic acids, creatine, taurocyamine and glycocyamine), studied in ileal ligated loops, increased intestinal calcium absorption in the rat. L-arginine was effective per os. Since these compounds are highly phosphorylable, a phosphorylation mechanism may be involved in the stimulation of calcium absorption. The phosphorylated derivative of creatine was detected in the ileal mucosa of rats receiving creatine in the ileal ligated loop. Modified amino acids, such as 5-methyl-L-glutamate, asparagine or glutamine, whose phosphorylable function was masked by a methyl or an amide radical, were not effective in enhancing calcium absorption. Assays in vitro showed that an ileal mucosa extract phosphorylated arginine, lysine, glycocyamine and taurocyamine in the presence of ATP, acting as a phosphate donor.