SELECTIVE IN SYNTHESIS LABELING OF PEPTIDES BY FLUOROCHROMES

A new method is described for producing fluorescently-tagged peptides containing specific internal derivatives of lysyl residues. The techni que employs the base-labile Boc-Lys(Fmoc)-COOH derivative with base-ca talyzed removal of the Fmoc protecting group during peptide synthesis and subsequent fluorescent derivatization of the deprotected epsilon-a mino group of lysine. By this technique, other lysine residues and the alpha-amino group of the fragment remain unmodified, which could have some value in studies where it might be required to tag a single indi vidual lysine residue within the peptide, but not the amino terminus. In spite of the fact that poly-substituted peptides are badly soluble and might seldom find a practical application, this technique also all ows the introduction of different fluorochromes at different lysyl res idues within the peptide, thus obtaining double fluorescence. The meth od, fast and easy, requires a limited number of manual operations duri ng the automatic synthesis of peptides. Although peptide synthesizers provided with an oscillating glass reactor are more suitable for the m anual interventions described, this technique might be also adapted to the newer instruments utilizing continuous-flow columns. (C) 1997 Els evier Science B.V.