Expeditious chemoenzymatic synthesis of CD52 glycopeptide antigens

Org Biomol Chem. 2010 Nov 21;8(22):5224-33. doi: 10.1039/c0ob00341g. Epub 2010 Sep 17.

Abstract

CD52 is a glycosylphosphatidylinositol (GPI)-anchored glycopeptide antigen found on sperm cells and human lymphocytes. Recent structural studies indicate that sperm-associated CD52 antigen carries both a complex type N-glycan and an O-glycan on the polypeptide backbone. To facilitate functional and immunological studies of distinct CD52 glycoforms, we report in this paper the first chemoenzymatic synthesis of homogeneous CD52 glycoforms carrying both N- and O-glycans. The synthetic strategy consists of two key steps: monosaccharide primers GlcNAc and GalNAc were first installed at the pre-determined N- and O-glycosylation sites by a facile solid-phase peptide synthesis, and then the N- and O-glycans were extended by respective enzymatic glycosylations. It was found that the endoglycosidase-catalyzed transglycosylation allowed efficient attachment of an intact N-glycan in a single step at the N-glycosylation site, while the recombinant human T-synthase could independently extend the O-linked GalNAc to form the core 1 O-glycan. This chemoenzymatic approach is highly convergent and permits easy construction of various homogeneous CD52 glycoforms from a common polypeptide precursor. In addition, the introduction of a latent thiol group in the form of protected cysteamine at the C-terminus of the CD52 glycoforms will enable site-specific conjugation to a carrier protein to provide immunogens for generating CD52 glycoform-specific antibodies for functional studies.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Acetylglucosamine / chemical synthesis
  • Acetylglucosamine / chemistry
  • Amino Acid Sequence
  • Antigens, CD / chemistry
  • Antigens, CD / metabolism*
  • Antigens, Neoplasm / chemistry
  • Antigens, Neoplasm / metabolism*
  • Biocatalysis
  • CD52 Antigen
  • Carbohydrate Conformation
  • Chromatography, High Pressure Liquid
  • Glycopeptides / chemistry
  • Glycopeptides / metabolism*
  • Glycoproteins / chemistry
  • Glycoproteins / metabolism*
  • Glycoside Hydrolases / metabolism*
  • Glycosylation
  • Humans
  • Molecular Sequence Data
  • Polysaccharides / chemistry
  • Polysaccharides / metabolism
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Substances

  • Antigens, CD
  • Antigens, Neoplasm
  • CD52 Antigen
  • CD52 protein, human
  • Glycopeptides
  • Glycoproteins
  • Polysaccharides
  • Glycoside Hydrolases
  • Acetylglucosamine