SYNTHESIS OF OLIGOMERIC L-LYSINE PEPTIDES BY SOLID-PHASE METHOD

The oligomeric peptides di- through deca-Llysine were synthesized by the solid-phase method by the use of a newly developed apparatus. The peptide chain was elongated stepwise by starting with L-lysine covalently bonded to an insoluble copolymer of 98% styrene and 2 % divinylbenzene. The α-amino group of lysine was protected with the t-butyloxycarbonyl group, and the ε-amino group was protected with the carbobenzoxy group. The t-butyloxycarbonyl group was selectively cleaved by 1 N HCl in acetic acid at room temperature for 30 min. After each coupling step, some peptide-resin was removed from the reaction vessel, dried, weighed, and deblocked with HBr gas in trifluoroacetic acid. It was found that 5 min of this treatment was sufficient to remove more than 90% of the peptide from the resin. The desired peptides were contaminated with lower homologs but chromatography on a carboxymethylcellulose column eluted with an exponential gradient of sodium chloride resulted in excellent separations. After lyophilizing and desalting on Sephadex G-15, the peptides were obtained in pure form. © 1969, American Chemical Society. All rights reserved.