Peptide stability in drug development. II. Effect of single amino acid substitution and glycosylation on peptide reactivity in human serum

Pharm Res. 1993 Sep;10(9):1268-73. doi: 10.1023/a:1018953309913.


The determination of peptide stability in human serum (HS) or plasma constitutes a powerful screening assay for eliminating unstable peptides from further development. Herein we report on the stability in HS of several major histocompatibility complex (MHC)-binding peptides. Some of these peptides are in development for the novel treatment of selected autoimmune disorders such as rheumatoid arthritis and insulin-dependent diabetes. For most of the l-amino acid peptides studied, the predominant degradation mechanism is exopeptidase-catalyzed cleavage. Peptides that were protected by d-amino acids at both termini were found to be more stable than predicted, based on additivity of single substitutions. In addition, N-acetylglucosamine glycopeptides were significantly stabilized, even when the glycosylation site was several amino acids from the predominant site(s) of cleavage. This indicates that long-range stabilization is possible, and likely due to altered peptide conformation. Finally, the effect of single amino acid substitutions on peptide stability in HS was determined using a model set of poly-Ala peptides which were protected from exopeptidase cleavage, allowing the study of endopeptidase cleavage pathways.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylglucosamine / chemistry
  • Amino Acid Sequence
  • Amino Acids / blood
  • Amino Acids / chemistry*
  • Chemical Phenomena
  • Chemistry, Physical
  • Chromatography, High Pressure Liquid
  • Endopeptidases / metabolism
  • Glycosides / blood
  • Glycosides / chemistry*
  • Humans
  • Hydrolysis
  • Kinetics
  • Major Histocompatibility Complex / physiology
  • Molecular Sequence Data
  • Peptide Hydrolases / metabolism
  • Peptides / blood
  • Peptides / chemistry*


  • Amino Acids
  • Glycosides
  • Peptides
  • Endopeptidases
  • Peptide Hydrolases
  • Acetylglucosamine