DEVELOPMENT OF A LINKER WITH AN ENHANCED STABILITY FOR THE PREPARATION OF PEPTIDE THIOESTERS AND ITS APPLICATION TO THE SYNTHESIS OF A STABLE-ISOTOPE-LABELED HU-TYPE DNA-BINDING PROTEIN

An S-alkyl-thioester-moiety-containing linker with an enhanced stability on a resin has been developed. A linker containing S-alkyl thioester with a spacer group, -CO-SC(CH3)2CH2CO-Nle-, was stable during the peptide chain elongation cycle. This thioester was stable under HF treatment conditions, and was rapidly activated by silver ions in the presence of N-hydroxysuccinimde (HONSu) to form a peptide bond. Using this linker, peptide segments covering the HU-type DNA-binding protein of Bacillus stearothermophilus (HBs), which was site-specifically labelled with H-2, C-13, and N-15, were prepared. Using these peptide segments, multi-labelled HBs was synthesized. Distinct signals of H-2, C-13, and N-15 in HBs were detected by NMR spectrometry.