Peptides conjugation

Bentin, T. and P.E. Nielsen. Superior duplex DNA strand invasion by acridine conjugated peptide nucleic acids. J. Am. Chem. Soc. 2003, 125, 6378-6379. 

Ljungstrom T., Knudsen H., Nielsen P.E. Cellular uptake of adamantyl conjugated peptide nucleic acids. Bioconjug. 

For the synthesis of the peptide-protein conjugates, peptides with a readive linker group, ie a maleimido group at the N-terminal amino function, were required. The synthesis of these peptides... 

Several alternative techniques can be exploited to conjugate peptides to preformed liposomes. They all involve hydrophobic anchors incorporated into the bilayers of vesicles that are able to react with modified or unmodified peptides. Their principles will be listed below, accompanied by pertinent references. 

The two examples from our work we are going to describe below are the design and study of liposomal diepitope constructs combining either (i) B and T-helper (Th) peptide epitopes, which induced particularly powerful humoral responses (21) (Fig. 3) or (ii) CTL and Th epitopes, which provided a powerful antitumor vaccine (74) (Fig. 4). For the production of these constructs we have conjugated peptides that contain a cysteine residue either at the N- or C-terminus, to the surface of preformed liposomes by reaction with thiol reactive functionalized phospholipids and/or PamaCys lipopeptide anchors (Fig. 2). To that end, we have developed strategies that give, in aqueous media, high... 

Figure 11.35 Helical conformational equilibria of dendron-modified alanine residue (A ) within a peptide-dendron conjugate. Peptide-dendron sequences are shown in the table form.

In this unit, Basic Protocol 1 presents a procedure using casein as substrate. The Alternate Protocol describes the modification of this procedure for use with a denatured hemoglobin substrate. Basic Protocol 2 presents a procedure using a chromaphore-conjugated casein derivative, azocasein. For quantitation, the authors have chosen to use either the BCA-based colorimetric assay unitbli) for soluble protein/peptides (in Basic Protocol 1) or the intrinsic absorbance of the chromaphore-conjugated peptide products (in Basic Protocol 2). 

This volume focuses on extensions of peptide chemistry into the novel areas of template-conjugated peptides, helical arrays of polypeptides, dendrimers, and C-terminally modified peptides. The volume concludes with an overview of the classic syntheses of representative peptide natural products. 

Resuspend the conjugated peptide in PBS at 1 mg/mL and store the unused portion at -20°C until further use. DMSO may also be used if the peptide-conjugate is extremely hydrophobic and difficult to solublize in PBS. 

Once immunoreactive sera is obtained, subsequent immunizations may continue ip or, a final boost with conjugated peptide in PBS may be given intravenously (iv) via tail-vein 3 d before fusion. Adjuvant is not used for the final iv boost. 

PNA are synthesized by solid-phase Fmoc/Bhoc chemistry (9-11). One to three Lys residues are generally added at the C-terminus to enhance aqueous solubility. Alter assembly (C to N), one additional Lys residue is added, followed by either a Cys residue (for disulfide conjugation) or by bromoacetyla-tion (for thioether conjugation). Peptides are also synthesized by solid-phase Fmoc chemistry as C-terminal amides, which may help to enhance bio-stability, and with a Cys residue at the C-terminus for conjugation by either disulfide or thioether methods. It is possible to place a Cys residue anywhere in the peptide sequence provided conjugation be desired at other sites. 

Liang, K. W., Hoffman, E. P., and Huang, L. (2000) Targeted delivery of plasmid DNA to myogenic cells via transferrin-conjugated peptide nucleic acid. Mol. Ther. 1(3), 236-243. 

Hudecz, F., Hilbert, A., Mezo, G., et al. (1993) Epitope mapping of 273-284 region of HSV glycoprotein D by synthetic branched polypeptide carrier conjugates. Peptide Res. 6, 263-271. 

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