title: Synthesis of a fluorescent derivative of amethopterin,.
abstract: Fluorescein isothiocyanate was treated with excess diaminopentane and the remaining unsubstituted amino group of the product was condensed, via a carbodiimide-promoted reaction, with a carboxyl group of amethopterin. The final product, a fluorescent derivative of amethopterin, was isolated by chromatography on AE-cellulose and preparative electrophoresis on polyacrylamide. It was shown to be homogeneous by analytical polyacrylamide electrophoresis and thin-layer chromatography. Proof of structure was provided by elemental analysis, absorbance spectra (at pH 7.0, lambdamax at 495 nm; fluorescence emission at 520 nm), and 1H NMR measurements. The fluorescent derivative of amethopterin inhibited transport of amethopterin into Lactobacillus casei and L1210 cells. It was also a good inhibitor of the L. casei and L1210 dihydrofolate reductases and could be used to provide a fluorescent label for the enzymes during polyacrylamide electrophoresis.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003864:Depression, Chemical; D003959:Diamines; D005452:Fluoresceins; D005453:Fluorescence; D005493:Folic Acid Antagonists; D007780:Lacticaseibacillus casei / Q000201:enzymology; D007939:Leukemia L1210 / Q000201:enzymology; D008727:Methotrexate / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D013056:Spectrophotometry, Ultraviolet; D013861:Thiocyanates
chemical_list: D003959:Diamines; D005452:Fluoresceins; D005493:Folic Acid Antagonists; D013861:Thiocyanates; D008727:Methotrexate