ABSTRACT
The biosynthetic reaction pathway leading to the natural product, 2-aminoethylphosphonate in Tetrahymena pyriformis has been elucidated. Incubation of [32P]PEP and [14C]PEP with T.pyriformis cellular homogenate fortified with Mg2+ and alanine/pyridoxal phosphate, yielded 2-aminoethylphosphonate as the minor reaction product (2-5% yield) and phosphoglycerate and pyruvate plus orthophosphate as the major products. Inclusion of thiamine pyrophosphate in the reaction mixture increased the yield of 2-aminoethylphosphonate by a factor of 10. Incubation of phosphonoacetaldehyde or phosphonopyruvate in the cellular homogenate also provided 2-aminoethylphosphonate. The cellular homogenate catalyzed the transformation of phosphonoacetaldehyde to 2-aminoethylphosphonate in an ca. 80% yield. However, the maximum yield of 2-aminoethylphosphonic acid obtained by use of phosphonopyruvate was only 15%. The major reaction pathways induced by treatment of phosphonopyruvate with the cellular extract involved its competitive conversion to PEP and pyruvate plus orthophosphate.
Subject(s)
Aminoethylphosphonic Acid/biosynthesis , Organophosphorus Compounds/biosynthesis , Tetrahymena pyriformis/metabolism , Acetaldehyde/analogs & derivatives , Acetaldehyde/metabolism , Alanine/metabolism , Animals , Magnesium/metabolism , Magnesium Chloride , Phosphoenolpyruvate/metabolism , Pyridoxal Phosphate/metabolism , Pyruvates/metabolism , Thiamine Pyrophosphate/metabolismSubject(s)
Aminoethylphosphonic Acid/biosynthesis , Aminoethylphosphonic Acid/pharmacology , Organophosphorus Compounds/biosynthesis , Organophosphorus Compounds/pharmacology , Phosphatidylcholines/metabolism , Tetrahymena/metabolism , Aminoethylphosphonic Acid/analogs & derivatives , Animals , Chromatography, Thin Layer , Phospholipids/analysis , Tetrahymena/drug effectsABSTRACT
1. The concentration of 2-aminoethylphosphonic acid (AEP) in 96 h cultures of Tetrahymena pyriformis W was studied in order to apply it as an indicator in the assay of the relative nutritive value (RNV; protozoa population with test protein:protozoa population with whole-egg powder) of protein. Foodstuffs and food mixtures of different protein contents and qualities were used as test samples. 2. RNV values based on AEP determination (RNVAEP) were compared with corresponding values calculated from protozoa counts (RNVpc), as well as with biological value (BV) and net protein utilization (NPU) of the same proteins assayed on rats. 3. Both for foodstuffs and food mixtures highly significant correlations were found between RNVAEP and RNVpc, RNVAEP and both BV and NPU, and RNVpc and both BV and NPU. 4. AEP content in the protozoal suspension was preferred to cell count as a measure of growth response, since it took into account large differences in cell dimensions that were observed between cultures grown with different test proteins.
