HIV-1 glycopeptides and derivatives; preparation and applications thereof

1. A method of simultaneously adding two homogeneous oligosaccharide N-glycans adjacent to a V3 domain of HIV gp120, the method comprising:

providing a precursor peptide comprising the V3 domain of HIV gp120 and two Asn amino acid residues wherein the two Asn residues are positioned adjacent to two cysteine residues of the V3 domain and wherein each of the two Asn amino acid residues comprise a N-acetylglucosamine (GlcNAc) moiety and act as a GlcNAc-peptide acceptor; and

conducting a transglycosylation reaction between an excess of a pre-assembled homogeneous oligosaccharide oxazoline and the two GlcNAc-peptide acceptors under the catalysis of Endo-A or Endo-M to generate two homogeneous oligosaccharide N-glycans positioned at the Asn amino acid residues adjacent to the V3 domain.

2. The method according to claim 1 , wherein the oligosaccharide oxazoline is a di- or tetrasaccharide oxazoline.

3. The method according to claim 1 , wherein the N-acetylglucosamine (GlcNAc) moiety is positioned on two Asn residues each adjacent to a cysteine residue of a sequence comprising amino acid residues of TSVEINCTRPNNNTRKRIRIQRGPGRAFVTIGKIGNMRQAHCNISRA (SEQ ID NO 1); or ESVEINCRPNNNTRKSIHIGPGRAFYTTGEIIGDIRQAHCNISRA (SEQ ID NO 2).

4. A method to synthesize a HIV glycoprotein comprising a V3 domain of gp120, the method comprising: synthesizing a peptide comprising the V3 domain of HIV gp 120 containing at least one N-acetylglucosamine (GlcNAc) moiety to form GlcNAc-peptide acceptor;

wherein the N-acetylglucosamine (GlcNAc) moiety is positioned at an Asn amino acid residue of the V3 domain; and transglycosylating a di- or tetrasaccharide oxazoline and the GlcNAc-peptide acceptor under the catalysis of the enzyme Endo-A to form the HIV glycoprotein including the V3 domain.

5. A method of simultaneously adding at least two pentasaccharide N-glycans to a glycopeptide comprising a V3 domain of HIV gp120, the method comprising:

providing a precursor peptide comprising TSVEINCTRPNNNTRKRIRIQRGPGRAFVTIGKIGNMRQAHCNISRA (SEQ ID NO 1) wherein two Asn residues, each adjacent to a cysteine residue comprise a GlcNAc moiety attached thereto, and

conducting a transglycosylation reaction between an excess of tetrasaccharide oxazoline and the two GlcNAc moieties under the catalysis of Endo-A or Endo-M to generate two homogeneous core pentasaccharide N-glycans on the glycopeptide.

6. A method of making a synthetic glycopeptide comprising a HIV gp120 V3-domain, the method comprising:

adding at least one synthetic oligosaccharide oxazoline to a GlcNAc-containing peptide precursor, wherein the GlcNAc-containing peptide precursor comprises the HIV gp 120 V3 -domain;

attaching the at least one synthetic oligosaccharide oxazoline to at least one Asn residue comprising a GlcNAc moiety in the presence of an enzyme selected from the group consisting of Endo-A and Endo-M, wherein the one Asn residue comprising the GlcNAc moiety is within the amino acid sequence of the V3 -domain or adjacent thereof.

7. The method according to claim 6 , wherein the enzyme is Endo-A.

8. The method according to claim 6 , wherein the enzyme is Endo-M.

9. The method according to claim 6 , wherein the synthetic oligosaccharide oxazoline comprises a di- or tetrasaccharide oxazoline.

10. The method according to claim 9 , wherein the synthetic oligosaccharide oxazoline comprises a disaccharide oxazoline.

11. The method according to claim 9 , wherein the synthetic oligosaccharide oxazoline comprises a tetrasaccharide oxazoline.