Peptide-Based Drug Design

Synthesis of Multiepitope Vaccine Construct 271
efficacy is expected, HATU can be replaced with TBTU/HObt or HBTU/HOBt
combinations.
4. For economical reasons, we purchase bulk amino acids and mix them with the
coupling reagents prior starting the synthesis. For our specific peptide synthesizer,
Protein Technologies sells prepackaged Fmoc-protected amino acids mixed with
coupling reagents, but these are limited to those with standard side chain protection
(notably Boc for lysine).
5. Cleavage of Dde protecting group: Transfer the peptide resin from the synthesizer
to a small flask fitted with a stopper. Add a solution of 2% hydrazine plus 1%
allyl alcohol in DMF. The allyl alcohol is needed to avoid partial hydrogenation of
the Aloc groups during Dde removal (22). Place a stopper to the flask and after 3
min decant the hydrazine solution. Repeat this treatment twice, filter the resin, and
wash with DMF. Hydrazine is a suspected carcinogen, so do the operations under
the hood, and exercise caution.
6. The tetrakis triphenylphosphine palladium fails to cleave the Aloc groups after
extended exposure to air. We recommend the use of the reagent from a freshly
opened bottle.
7. The generally observed difficulties observed with palladium compounds prompted
the development of novel deprotection strategies and selectively removable
amino protecting groups (23). Among the alternative allyl deprotection
strategies, diisobutyl aluminum hydride (DIBAL) in the presence of dichlorobis
(diphenylphosphino) propane nickel [(dpppNiCl2)] in an aprotic solvent removes
N-allyl groups in good yields (24).
References
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targets. J. Pept. Sci. 11, 697–706.
4. Dietzschold, B., Gore, M., Marchandiar, D., et al. (1990) Structural and immunological
characterization of a linear virus-neutralizing epitope of the rabies
virus glycoprotein and its possible use in a synthetic vaccine. J. Virol. 64,
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