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We have discussed in some detail a variety of experimental studies which were designed to elucidate the conformational and dynamic properties of gramicidin and alamethicin. Although the behavior of these peptides is by no means fully characterized, these studies have already permitted aspects of ion channel activity to be understood in molecular terms.(More)
The alpha-helix is a key structural element in a wide range of peptides and proteins. We report here the design, synthesis, and characterization of a modified peptide in which the helix content can be reversibly photoregulated. The peptide contains two cysteine residues that are cross-linked by an azobenzene derivative in an intramolecular fashion. In(More)
Photocontrolled transcription factors could be powerful tools for probing the role of transcriptional processes in settings that are spatially or temporally complex. We report the structure-based design of a photocontrolled bZIP-type DNA binding protein that is a hybrid of the prototypical homodimeric bZIP protein GCN4 and photoactive yellow protein (PYP),(More)
Photo-control of protein conformation could prove useful for probing function in diverse biological systems. Recently, we reported photo-switching of helix content in a short peptide containing an azobenzene cross-linker between cysteine residues at positions i and i + 7 in the sequence. In the original sequence, underlying residues at positions i + 3 and i(More)
The photoisomerization of azobenzene has been known for almost 75 years but only recently has this process been widely applied to biological systems. The central challenge of how to productively couple the isomerization process to a large functional change in a biomolecule has been met in a number of instances and it appears that effective photocontrol of a(More)
The interaction of the voltage-dependent channel-forming peptide alamethicin with dioleoylphosphatidylcholine (DOPC) small unilamellar vesicles (SUV) has been studied using circular dichroism spectroscopy over a range of wavelengths and temperatures. Evidence is presented for the existence of two distinct membrane-bound states of the peptide which reflect(More)
Although noted as hydrophilic residues with helix-breaking potential, proline residues are observed in putatively alpha-helical transmembrane (TM) segments of many channel-forming integral membrane proteins. In addition to the recognized property of X-Pro peptide bonds (where X = any amino acid) to occur in cis as well as trans isomeric states, the tertiary(More)
The peptide alamethicin forms channels with a variety of conductance states. Selective stabilization of a particular state should simplify the task of understanding conductance in terms of channel structure. We synthesized two different covalent dimers of alamethicin in which peptides were linked at their C-terminal ends by flexible tethers. Both dimeric(More)
The synthesis and characterization of alamethicin pyromellitate (Alm-PM), a derivative of the channel-forming peptide alamethicin bearing three negative charges at the C-terminus, is described. The self-association of Alm-PM in small unilamellar vesicles of dioleoylphosphatidylcholine (DOPC), monitored using circular dichroism (CD) spectroscopy, occurs much(More)