ONLY WEAK DEPENDENCE OF THE PROTECTED PEPTIDES SOLUBILITY IN ORGANIC-SOLVENTS ON THEIR AMINO-ACID-SEQUENCE

The adequacy of the hypothesis that the protected peptide solubility o nly weakly depended on their amino acid sequence was confirmed by the evaluation of the beta-sheet-structure stability of protected peptides . As the beta-sheet-structure stability of protected peptides is relat ed with their solubility, it is investigated by the solvent-titration method using the protected host-guest peptides, Boc-(X-Glu(OBzl)-Ala-L eu-Gly)(n)-OPac (n=1, 2) which have the same amino acid composition wi th Boc-(X-Ala-Glu(OBzl)-Leu-Gly)(n)-OPac (n=1, 2) studied previously. In fact, the results show concurrently that the beta-sheet-structure s tability of pentapeptides is useful for the estimation of protected pe ptide solubility in organic solvents and only weakly dependent on thei r amino acid sequence. It is also little weakly dependent on the solva tion mechanism, by which peptides they solvate with an electron accept or or donor solvent. The beta-sheet-structure stability of protected d ecapeptides is also strongly dependent on their amino acid composition and only weakly dependent on their amino acid sequence. The significa nce of the hypothesis for the prediction of the protected protein solu bility is briefly discussed.