Peptide synthesis on chitin.

The use of chitin as a support for solid-phase peptide synthesis is described and illustrated by synthesis of four peptides, varying in length from 10 to 29 residues. Syntheses were performed in a continuous-flow peptide synthesizer, using Fmoc chemistry. A cleavable linker, p-[(R,S)-alpha-[1-(9H-fluoren-9-yl)-methoxyformamido]-2,4-di methoxybenzyl]- phenoxyacetic acid, was attached to chitosan at the desired substitution level, and the complex acetylated to yield a linker substituted chitin. The effects of temperature, solvents and degree of linker substitution on the syntheses were studied. Acyl carrier peptide (ACP) synthesis studies indicated that temperature was the single most important parameter. Increasing the temperature of the synthesis from 20 to 55 degrees C resulted in an enormous improvement of this synthesis, with about 90% of the crude product being the correct peptide. Denaturing solvents, such as DMSO, could be used without significant effect on the flow properties of the support. The synthesis of one peptide was mainly improved by lowering the degree of substitution from 0.3 to 0.1 mmol/g, suggesting peptide aggregation was a problem in this case. The results of three syntheses on chitin were comparable with those obtained with a commonly used commercial support. This work shows that, under appropriate conditions, chitin can be utilized directly as a support for peptide synthesis.