Editing Synthesis of Peptide-Spermine (section)

== Peptides and Peptide Conjugates<br> ==

<br> [00099] Peptides were synthesized using automated solid phase peptide synthesis as described, e.g., in Stewart et al. (1984) Solid Phase Peptide Synthesis, Pierce Chemical Company, Rockford, Ill. Peptides were synthesized using a polyamide-Kieselguhr composite resin and a Milligen 9050 peptide synthesizer (Milligen/Biosearch, Burlington, Mass.). Coupling cycles were performed according to the manufacturer's recommendations. 9-Fluorenyl-methyloxy-carbonyl (Fmoc) amino acid was activated as a pentafluorophenyl ester (--OPfp ester); Peptides were deblocked using; (1) 20% piperidine in N,N-dimethylformamide (DMF) for alpha-amino groups; Peptides were cleaved from the resin and deprotected using 95% trifluoroacetic acid (TFA), (2) Reagent R [TFA (90%), thioanisol (5%), ethylene dithiole (3%) and anisole (2%)], Reagent B [TFA (88%), phenol (5%), triisopropylsilane (2%) and water (5%)] or Reagent T [TFA (95%), triisopropylsilane (5%); Deprotection agent being chosen as is understood in the art based on the protecting groups used and the type of amino acid residues in the peptide; Crude peptides were precipitated and washed with ether. Peptides were purified by high pressure liquid chromatography on a Vydac C-18 reverse-phase column using a Waters HPLC system. The mobile phase consisted of a gradient from 0.01% TFA in 95% water/acetonitrile to 0.01% TFA in 25% water/acetonitrile. Peptides were characterized by HPLC, amino acid analysis and mass spectrometry (ES or MALDI-TOF). Exemplary peptide sequences useful in this invention are listed in Tables 1-3.<br>

<br> [00100] It was found that certain peptides that were only partially deblocked, i.e., at least one amino acid protecting group had not been removed, showed significant enhancement of transfection. Appropriate choice of deprotection agent allows selective synthesis of peptides which retain a desired protecting group. For example, deprotection with Reagent T does not remove the Mtr protecting group on arginines allowing the synthesis of partially deblocked peptides with Mtr groups remaining on R residues.<br>