engleski

Ferrocene chromophore as a circular dichroism probe for conformational analysis of short peptides

The perturbation of inherently achiral chromophore, caused by covalently attached chiral system, causes the modification of its chiroptical properties and can give rise to intense CD-activity in the spectral region of the absorbing chromophore. We have recently demonstrated that ferrocene-functionalized homo- and heterochiral dipeptides Boc-(AA)2- NH-Fc are able to form ordered conformations that resemble the naturally occurring beta- and gamma- turns. Furthermore, the strong bands in the CD-spectra of these bioorganometallics originate from the transfer of chiral information from the local secondary structure to ferrocene chromophore. As a continuation of this study, we have synthesized four enantiomeric pairs of derivatives of aminoferrocene and homo- and heterochiral tripeptide sequences (Boc-Pro-Pro-Ala-NH-Fc) and subjected them to a detailed conformational study. Results obtained by means of spectroscopic analysis (NMR-, IR- and CD- spectroscopy) and computational chemistry methods indicate that conformational preferences of these derivatives, and thus the ability to form specific secondary structure elements (turns, minimal helices), strongly depend on chirality of the constituent amino acids. Moreover, different conformations of the peptide sequence give rise to different shapes and intensities of CD-bands around the UV/Vis absorption maximum of the ferrocene chromophore.

Conformational analysis ; Ferrocene ; Peptide ; CD-spectroscopy

nije evidentirano