A 500 MHz 1H NMR spectroscopic study of Met5-enkephalinamide in aqueous solution: ethanol induced conformational...

An analysis of spin coupling constants, less than 3J greater than C alpha H-NH, from a high resolution 500 MHz 1H NMR study of [Met5]-enkephalinamide in aqueous solution, suggested that beta-sheet structure is the likely conformer. The effect of ethanol on the conformation of [Met5]-enkephalinamide in aqueous solution was investigated. From the upfield drift of observed chemical shifts and changes in coupling constants, especially of the amide NH resonances, it is concluded that ethanol disrupts the conformation possibly by influencing the hydrogen bonding. The above observation is consistent with a recent study of the ethanol induced conformational changes occurring in [Met5]enkephalinamide [Rapaka, R.S. et al. (1986) Life Sciences 39, 837-842].