Synthesis and biological evaluation of a novel pyroglutamyl-modified TRH analogue

The TRH analogue 3, incorporating the (S)-isothiazolidine-1,1-dioxide-3-carboxylic acid (I) moiety in place of the native L-pyroglutamic acid (pGlu) residue, has been synthesized and fully characterized by H-1 and C-13 NMR. The effects of replacing pGlu with its sulphonamido counterpart on biological activity have been investigated. This peptide, which is significantly stabilized towards hydrolysis by pyroglutamyl peptidase type I (PP I, EC 3.4.19.3), has shown to maintain in vitro prolactin-releasing activity. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.