Synthesis, biological activity and conformational analysis of cyclic GRF analogs

Publisher Website
Google Scholar
Abstract
A novel cyclic GRF analog, cyclo(Asp8‐Lys12)‐[Asp8,Ala15]‐GRF(1‐29)‐NH2, i.e. cyclo8.12[Asp8,Ala15]‐GRF(1‐29)‐NH2, was synthesized by the solid phase procedure and found to retain significant biological activity. Solid phase cyclization of Asp8 to Lys12 proceeded rapidly (∼2h) using the BOP reagent. Substitution of Ala12 with d‐Ala2 and/or NH2‐terminal replacement (desNH2‐Tyr1 or N‐MeTyr1) in the cyclo8.12[Asp8,Ala15]‐GRF(1‐29)‐NH2 system resulted in highly potent analogs that were also active in vivo. Conformational analysis (circular dichroism and molecular dynamics calculations based on NOE‐derived distance constraints) demonstrated that cyclo8.12[Asp8,Ala15]‐GRF(1‐29)‐NH2 contains a long α‐helical segment even in aqueous solution. A series of cyclo8.12 stereoisomers containing d‐Asp8 and/or d‐Lys12 were prepared and also found to be highly potent and to retain significant α‐helical conformation. The high biological activity of cyclo8.12[N‐MeTyr1,d‐Ala2,Asp8,Ala15]‐GRF(1‐29)‐NH2 may be explained on the basis of retention of a preferred bioactive conformation.

This publication has 28 references indexed in Scilit: