Pteroylglutamates of higher plant tissues

Abstract

The levels of pteroylglutamate derivatives in whole leaf extracts and non-aqueously isolated chloroplasts of pea and maize seedlings have been determined by differential microbiological assay. A number of derivatives capable of supporting the growth of Lactobacillus casei (ATCC 7469), Streptococcus faecalis (ATCC 8043) and Pediococcus cerevisiae (ATCC 8081) were separated by DEAE-cellulose column chromatography. The principal derivatives present in all extracts were methyl and formyl compounds of tetrahydropteroylglutamic acid. Increases in the levels of these derivatives following treatment with mammalian and avian γ-glutamyl carboxypeptidases suggested that additional highly conjugated pteroylglutamates were present in all extracts. The levels of pteroylglutamate derivatives in isolated chloroplasts were affected by the isolation method employed. The pteroylglutamate contents of non-aqueously isolated chloroplasts were approximately four times greater than the levels found in chloroplasts isolated in aqueous media. Approximately 96% of the pteroylglutamates in non-aqueously isolated chloroplasts were solubilized after a brief sonication treatment in the presence of ascorbate.