.gif?ad=15653&adview=true)
Tertiary Structure of H-Pro-Leu-Gly-NH2, the Factor That Inhibits Release of Melanocyte Stimulating Hormone, Derived by Conformational Energy Calculations
- Laboratoire de Chimie Biologique, Université Libre de Bruxelles, 1640 Rhode St. Genèse, Belgium
- *Department of Physiology and Biophysics, Mount Sinai School of Medicine of the City University of New York, New York, New York 10029
- The Medical Research Center, Brookhaven National Laboratory, Upton, New York 11973
Abstract
Conformational energy calculations were carried out on H-Pro-Leu-Gly-NH2, the factor that inhibits the release of melanocyte stimulating hormone, and its biologically active analog, H-Pro-Ala-Gly-NH2. Both peptides were found to be relatively compact molecules that retain, however, some degree of flexibility. After structure refinement, H-Pro-Leu-Gly-NH2 possesses at least three preferred compact conformations. Two of these conformations occupy rather broad and flat energy troughs, while a third occupies a narrow and deep potential energy well. This third structure, which consists of a 10-membered β-turn closed by a (4 → 1) hydrogen bond between the proton of the trans carboxamide of Gly and the C=O of Pro, is the one that was proposed for H-Pro-Leu-Gly-NH2 in dimethylsulfoxide and was also found by x-ray analysis.
