Coloured peptides: synthesis, properties and use in preparation of peptide sub-library kits.
Several methods were developed for the solid-phase synthesis (SPPS) of coloured peptides and peptide libraries. At first a bifunctional red compound, 4-(4-(N-ethyl-N-(3-(tert-butyloxycarbonyl)aminopropyl)amino)phenylazo)be nzoic acid (Boc-EPAB), was coupled with chloromethyl resin to obtain a new solid support suitable for SPPS using Boc chemistry. Peptides synthesized on this coloured resin had the chromophore at their C-termini. N-terminally coloured peptides were synthesized on a traditional solid support, coupled with chromophoric carboxylic acid before cleavage. A model pentapeptide, Phe-Ala-Val-Leu-Gly, and its ten derivatives were synthesized and their properties studied. It was found that the presence of chromophores decreases the water solubility of peptides. However, insertion of solubilizing tags (penta-lysine sequences or polyoxyethyl chains) into the molecule of any coloured derivative resulted in enhancement of the solubility. The RP-HPLC hydrophobicity indexes (phi0) of the coloured peptides were also determined because phi0 values are closely related to their water solubility. A coloured pentapeptide library was synthesized using the portioning-mixing method. Each component of this library contained the red azo dye (EPAB) and the penta-lysine tag. Before the last coupling step the samples were not mixed. All of the 19 sub-libraries obtained after cleavage were readily soluble in water, giving intense red solutions. The effect of chromophore (EPAB) and/or penta-lysine solubilizing tag on the biological activity was also studied. Potencies of the bovine neurotensin 8-13 fragment and its different coloured and penta-lysine derivatives were compared in isolated longitudinal muscle strips of guinea pig ileum. It was shown that the hexapeptide with penta-lysine tag had almost the same activity as the 8-13 fragment itself. The activity of the EPAB-derivative was found to be rather low. However, the presence of the solubilizing tag in the coloured hexapeptide compensated the negative effect of the chromophore.
Department of Organic Chemistry, Eötvös Loránd University, Budapest, Hungary.
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Sebestyén
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Szendrei
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Mák
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M
Dóda
E
E
Illyés
G
G
Szókán
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K
Kindla
W
W
Rapp
P
P
Szegö
E
E
Câmpian
A
A
Furka
D062365:Aminobenzoates / Q000737:chemistry*; D003116:Color; D013058:Mass Spectrometry; D015394:Molecular Structure; D009496:Neurotensin / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D019151:Peptide Library; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D012995:Solubility; D062366:para-Aminobenzoates
C114916:4-(4-(N-ethyl-N-(3-(tert-butyloxycarbonyl)aminopropyl)amino)phenylazo)benzoic acid; D062365:Aminobenzoates; D010446:Peptide Fragments; D019151:Peptide Library; D010455:Peptides; D062366:para-Aminobenzoates; D009496:Neurotensin; C054381:neurotensin (8-13)