Proton magnetic resonance studies of conformation and flexibility of enkephalin peptides


ENKEPHALIN, an endogenous pentapeptide which has the analgesic properties of morphine1, has recently been isolated, purified and characterised both chemically and pharmacologically2,3. The fact that enkephalin and the opiates interact with the same receptor raises the possibility that the similarity in their function might be based on common structural features4,5. Particular attention has been paid to the geometric relationship between the aromatic ring of the tyrosine residue and the terminal amino group of enkephalin compared with the known geometry of similar functional groups in morphine. The relative spatial disposition of the phenylalanine and tyrosine aromatic side chains is also of special interest because of the possible resemblance of enkephalin to oripavine4,5. So far, however, no experimental determination of conformational parameters has appeared. Here we report proton magnetic resonance (PMR) studies of Met5-enkephalin which indicate that the methionine amino proton is involved in a hydrogen bond, most probably within a Gly–Gly–Phe–Met type I β turn, but not with a turn involving Tyr–Gly–Gly–Phe as proposed previously6. Although our data exclude a γ turn, they do not rigorously exclude other conformations, especially if these have small statistical weights.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

    Belluzi, J. D., et al., Nature, 260, 625–626 (1976).

  2. 2

    Hughes, J., et al., Nature, 258, 577–579 (1975).

  3. 3

    Waterfield, A. A., Hughes, J., and Kosterlitz, H. W., Nature, 260, 624–625 (1976).

  4. 4

    Horn, A. S., and Rodgers, J. R., Nature, 260, 795–797 (1976).

  5. 5

    Bradbury, A. F., Smyth, D. G., Snell, C. R., Birdsall, N. J. M., and Hulme, E. C., Nature, 260, 793–795 (1976).

  6. 6

    Bradbury, A. F., Smyth, D. G., and Snell, C. R., Nature, 260, 165–166 (1976).

  7. 7

    Kopple, K. D., Ohnishi, M., and Go, A., J. Am. chem. Soc., 91, 4264–4272 (1969).

  8. 8

    Ohnishi, M., and Urry, D. W., Biochem. biophys. Res. Commun., 36, 194–202 (1969).

  9. 9

    Nemethy, G., and Printz, M. P., Macromolecules, 5, 755–758 (1972).

  10. 10

    Glickson, J. D., Urry, D. W., Havran, R. T., and Walter, R., Proc. natn. Acad. Sci. U.S.A., 69, 2136–2140 (1972).

  11. 11

    Pachler, K. G. R., Spectrochim. Acta, 20, 581 (1964).

  12. 12

    Wyssbrod, H. R., and Gibbons, W. A., Survey of Progress in Chemistry, 6, (edit. by Scott, A. I.), 209–325 (Academic, New York and London 1973).

  13. 13

    Goldstein, A., Aronow, L., and Kaiman, S. M., Principles of Drug Action, 50–60 (Harper and Row, New York, 1969).

  14. 14

    Wessels, P. L., Feeney, J., Gregory, H., and Gormley, J. J., J. chem. Soc. Perkin, II, 1691–1698 (1973).

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.