THE IN VITRO SYNTHESIS OF GLYCINE BY RUMEN PAPILLAE

Following aerobic in vitro incubation of papillae from the ventral sac of the bovine rumen, amino acids released into the incubation medium were isolated using a rapid ion exchange procedure and measured quantitatively by gas-liquid chromatographic separation of the isobutyl-N(0)-heptafluorobutyryl esters. Of the potential precursors of the carbon skeleton of glycine that were added as substrates, only glyoxylate and serine (0.5–2 mM) resulted in enhanced glycine release while 10 mM glycolaldehyde, glycollate, glyoxal or oxalate or 1 mM monoethanolamine or hydroxyproline did not specifically influence glycine release. Each increase in glyoxylate concentration through 5, 10 or 20 mM caused an increased glycine release. In the presence of formate, inclusion of glycine as the added substrate increased serine release. Oxalate caused a non-specific release of amino acids. In the presence of glyoxylate, alanine and glutamate (1 mM) were effective precursors of the amino group of glycine.