Editing Synthesis of Peptide-Spermine (section)

== <br>Synthesis of Polyamine Conjugated Peptides<br> ==

<br> [00101] Peptides can be modified with polyamines, such as spermine, using an automated peptide synthesizer. Either the Fmoc or Boc chemistries can be used. For example, spermine can be attached to the N-terminus of a peptide as illustrated in Scheme I. 5-Carboxy spermine and Boc-protected 5-carboxy spermine can be synthesized as described in Behr, J-P. et al. (1989) Proc. Natl. Acad. Sci., 86:6982-6986. Fmoc-carboxy spermine can be synthesized by treating carboxy spermine with 9-fluorenylmethyl chloroformate. Fmoc-carboxy spermine or the pentafluorophenyl ester can be used in the synthesizer to obtain spermine-modified peptides. More than one polyamine can be attached in this manner to a given peptide using an appropriate combination of protecting groups.<br>

<br>N.sup.I,N.sup.II,N.sup.III,N.sup.IV -tetra(9-fluorenylmethoxycarbonyl)-5-carboxyspermine (Fmoc-carboxyspermine)<br> [00102] 5-Carboxy spermine (11.0 g) was dissolved in 100 ml water. The solution was chilled on ice and diluted with 200 ml dioxane and flushed with argon. A solution of 50 g of 9-fluorenylmethyl chloroformate (Fmoc-Cl) in 200 ml of dioxane was slowly added to the chilled carboxy spermine. The reaction mixture was stirred under argon at 4° C. for an hour and at room temperature overnight under argon. The reaction was monitored by TLC (silica Gel, CHCl.sub.3 /MeOH::9/1). The reaction mixture was poured into 1.5 L ice cold water (1.5 L) and extracted with ethyl acetate (2 L). The organic layer was separated and sequentially extracted with 400 ml of 1 N HCl (2×) and 300 ml saturated NaCl. The organic layer was dried over Na.sub.2 SO.sub.4 and concentrated on a rotary evaporator. The resultant gummy material was subjected to flash chromatography (silica, CHCl.sub.3 /MeOH::95/5) to yield 25.5 g of the desired material as a white fluffy solid. ##STR2##<br>