Characterization of the Pools of 5, 10-Methylenetetrahydrofolates and Tetrahydrofolates in Xenografts of Human Colon Adenocarcinoma

The method for measuring polyglutamate forms of CH2-H4PteGlu and HiPteGlu, by entrapment in ternary complexes with |6-3H]5-fluoro-2'-deoxyuridylate and Lactobacillus casei thymidylate synthase has been characterized. Results demonstrated that (a) the relationship between concentration of CH2-H4PteGlu and complex isolated on nondenaturing gels was dependent upon the number of glutamyl residues, and an alternative method for data analysis has been presented, (6) the relationship was linear over a 100-fold change in concentration, (c) formation of isolatable complex was time dependent, (d) noncovalent complexes formed with PteGlu2_5 could be isolated only at concentrations considerably higher than those required for CH2-H4Pte Glu1-6, and (e) endogenous deoxyuridylate would be unlikely to interfere significantly with the assay. The distribution of polyglutamates of CH2-H4PteGlu and the combined.