SYNTHESIS OF FOLATE DERIVATIVES IN AERATED STORAGE TISSUE DISKS

Microbiological assay of extracts prepared from carrot [Daucus carota], potato [Solanum tuberosum], turnip [Brassica campestris] and beet [Beta vulgaris] storage tissue disks revealed that folate derivatives were synthesized during a 48 h aeration period in sterile distilled water. The composition of the folate pool in carrot was examined by DEAE-cellulose column chromatography, .gamma.-glutamylcarboxypeptidase treatment and differential assay of individual derivatives using Lactobacillus casei and Streptococcus faecalis. The principal folates were polyglutamates of formyl and methyl tetrahydrofolate. Smaller quantities of the corresponding mono- and di-glutamates were also detected. The latter derivatives occurred in pools having a high degree of metabolic turnover. The specific activities of 3 enzymes catalyzing production of these derivatives from tetrahydrofolate increased during the first 12 h of aeration. Amino acid analyses revealed that folate synthesis in carrot disks was accompanied by depletion of free serine and by net synthesis of free and protein methionine.