1H‐NMR of met‐enkephalin in AOT reverse micelles

1H‐NMR spectra of Met‐enkephalin dissolved in AOT/isooctane reverse micelles are reported at various temperatures. The NH temperature coefficients are compared with those obtained for the same peptide in normal SDS micelles, in bulk water, and in DMSO. The results show that the opioid molecule undergoes the greatest folding in the reverse micellar system. Shift reagents selectively dissolved in the water pools or in the hydrophobic matrix affect the Phe‐4 or the Tyr‐1 aromatic resonances, respectively. This suggests that the phenylalanyl sidechain is spatially close to the carboxyl group at the C‐terminus, whereas the tyrosyl ring points towards the outer region of the AOT micelles.