4‐Cyano‐α‐methyl‐l‐phenylalanine as a Spectroscopic Marker for the Investigation of PeptaibioticMembrane Interactions |
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Authors: | Marta De?Zotti Sara Bobone Annalisa Bortolotti Edoardo Longo Barbara Biondi Cristina Peggion Fernando Formaggio Claudio Toniolo Andrea Dalla?Bona Bernard Kaptein Lorenzo Stella |
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Institution: | 1. ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, IT‐35131 Padova;2. Department of Chemical Sciences and Technologies, University of Rome ‘Tor Vergata', IT‐00133 Rome;3. DSM Innovative Synthesis BV, P.O. Box 18, NL‐6160 MD Geleen |
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Abstract: | Two analogs of the ten‐amino acid residue, membrane‐active lipopeptaibiotic trichogin GA IV, mono‐labeled with 4‐cyano‐α‐methyl‐L ‐phenylalanine, a potentially useful fluorescence and IR absorption probe of the local microenvironment, were synthesized by the solid‐phase methodology and conformationally characterized. The single modification was incorporated either at the N‐terminus (position 1) or near the C‐terminus (position 8) of the peptide main chain. In both cases, the replaced amino acid was the equally helicogenic α‐aminoisobutyric acid (Aib) residue. We performed a solution conformational analysis by use of FT‐IR absorption, CD, and 2D‐NMR spectroscopies. The results indicate that both labeled analogs essentially maintain the overall helical propensity of the naturally occurring lipopeptaibiotic. Peptide? membrane interactions were assessed by fluorescence and ATR‐IR absorption techniques. Analogies and differences between the two peptides were highlighted. Taken together, our data confirm literature results that some of the spectroscopic parameters of the 4‐cyanobenzyl chromophore are sensitive markers of the local microenvironment. |
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Keywords: | L‐Phenylalanine 4‐cyano‐α ‐methyl‐ Membrane activity Peptaibols Solid‐phase synthesis |
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