FLUORESCENCE ENERGY-TRANSFER IN THE SERIES OF LEUCINE-ENKEPHALIN ANALOGS

Leucine-enkephalin contains only the one chromophore suitable for fluo rescence study - tyrosine residue. To study fluorescence energy transf er second chromophore is required. Therefore we synthesized a leucine- enkephalin (as a model donor compound) and series of analogues contain ing additionally to tyrosine in position 1 (donor) a wide selection of acceptors (thioamide moiety, anthranilic acid amide, (p-nitro)phenyla lanine) in different positions: [Leu-NH25]-enkephalin (I), [LeuPSI[CSN H25]-enkephalin (II), [GlyPSI[CSNH]Phe3,4,Leu-OMe5]-enkephalin (III), [Phe(p-NO2)4,Leu-NH25]-enkephalin (IV), [Leu5 Ant-NH26-enkephalin (V). The determined inter-chromphoric distances by means of fluorescence s pectroscopy have shown a great similarity to those obtained from molec ular mechanics calculations.