AMINO-ACID-SEQUENCE AND D L-CONFIGURATION DETERMINATION OF PEPTIDES UTILIZING LIBERATED N-TERMINUS PHENYLTHIOHYDANTOIN AMINO-ACIDS/

In this paper, we examined the possibility of using conventional Edman degradation with phenyl isothiocyanate for the simultaneous determina tion of both the sequence and the D/L-configuration of amino acids in peptides. Boron trifluoride and HCl-methanol (1:10, v/v) were adopted as the cyclization/cleavage and conversion reagents instead of the res pective use of anhydrous trifluoroacetic acid (TFA) and 20% aqueous TF A to suppress the amino acid residue racemization. The enantiomeric se paration of 18 phenylthiohydantoin amino acids was achieved on two typ es of chiral stationary phases bonded with beta-cyclodextrin. The prop osed Edman procedure was applied to a synthetic beta-amyloid 1-16 with all L-forms as a model peptide, affording the amino acid sequence and configuration determination up to 12 residues. (C) 1998 Elsevier Scie nce B.V. All rights reserved.