Identification of glutamate chain lengths of endogenous folylpoly-gamma-glutamates in rat tissues.

A simplified procedure for the determination of the glutamate chain lengths of endogenous tissue folate is described. Natural pteroylpoly-gamma-glutamates in tissue extracts, irrespective of their one-carbon moiety, were converted by a reductive cleavage procedure to a homologous series of p-aminobenzoylpoly-gamma-glutamates, differing only in glutamate chain length. Desalting and concentration of the extracts were achieved by absorbing the derivatives on active charcoal followed by their elution with ethanol:ammonia. Aminobenzoylpolyglutamates were separated by DEAD-cellulose chromatography and quantitated by a colorimetric procedure for primary aromatic amines. The major endogenous folates in rat liver and kidney were pteroylpentaglutamate derivatives with smaller amounts of pteroyltetra- and hexaglutamate.