S. Ranganathan et al., PROTEIN-FOLDING - THE SYNTHESIS AND CONFORMATIONAL STUDIES ON CYSTINYL-CYSTINYL-CYSTINE [-CSSCCSSCCSSC-] A NOVEL CROSS-LINKING MOTIF, Tetrahedron, 52(29), 1996, pp. 9823-9834
The cysteine capped, ends protected cross linked motifs 6 and 7, arisi
ng from pairs of proximally placed cysteines wherein within a 22 atom
framework are inscribed 3 disulphide bridges and 2 peptide linkages, h
ave been prepared and their conformations derived by detailed H-1 NMR
studies and molecular modeling protocols, where excellent agreement wa
s seen. Both compounds 6 and 7 possess a C-2 symmetric hydrogen bonded
pair involving the peptide NH and the CO of the proximate N-protectin
g group (Boc or Z). The nature of the latter profoundly influences the
conformation. Thus, in 6 where the unit is Boc a bend conformation wa
s promoted by hydrophobic interactions; alternatively in 7 with a Z-pr
otecting group the conformation was linear. Compounds 6 and 7 have muc
h promise in diverse aspects of protein design. Copyright (C) 1996 Els
evier Science Ltd