Proton n.m.r. investigation of conformational influence of penicillamine residues on the disulfide ring system of opioid receptor selective somatostatin derivatives |
| |
| Authors: | E E Sugg D Tourwe W Kazmierski V J Hruby G Van Binst |
| |
| Institution: | Department of Chemistry, University of Arizona, Tucson. |
| |
| Abstract: | Three cyclic disulfide analogs related to somatostatin, D-Phe(1)-cyclo(Cys(2)-Tyr(3)-D-Trp(4)-Lys(5)-Thr(6)-Xxx(7))-Thr(8)- NH2 (where Xxx = L-Pen 1; L-Cys 3; or D-Pen 4) were examined in DMSO-d6 by one- and two-dimensional proton n.m.r. spectroscopy in order to analyze the conformational influence of the position-7 residue on the 20-membered disulfide ring. From these studies it was concluded that all three analogs maintain a beta II' turn solution conformation for the core tetrapeptide -Tyr(3)-D-Trp(4)-Lys(5)-Thr(6)-. However, the disulfide conformation differs in the analogs, with 1 and 3 having a left-handed and 4 a right-handed disulfide chirality. |
| |
| Keywords: | |
|
|
