Processes at Biological Membranes

18. Cathelicidine LL-37 – A Peptide of our innate Antimicrobial immune system

Cathelicidins are a family of host defense antimicrobial peptides in mammalian species. Among them, LL-37 is the only peptide of this family found in humans. We combine microbiology, spectroscopy and simulations to unravel its mode of action.

de Miguel Catalina & Forbrig et al., Biochemistry, 2019
The C-Terminal VPRTES Tail of LL-37 Influences the Mode of Attachment to a Lipid Bilayer and Antimicrobial Activity.
DOI: 10.1021/acs.biochem.8b01297

14. Monitoring the Catalytic Proton Translocation Across the Membrane by Respiratory Complex I

Using a pH-dependent self-assembled monolayer (SAM), based on amino thiophenol, we monitor the protein orientation-dependent directionality of the catalytic proton translocation induced by addition of NADH.

Gutierrez-Sans & Forbrig et al., Langmuir, 2018
Catalytic activity and proton translocation of reconstituted respiratory complex I monitored by surface-enhanced infrared absorption spectroscopy.
DOI: 10.1021/acs.langmuir.7b04057

12. Monitoring how Transmembrane Electrostatics reorient a-helices in Membranes

Antimicrobial peptides are the first line of defense after contact of an infectious invader, often acting via interactions with the target membrane. The transmembrane electrostatics can play a major governing role in antimicrobial action. We show, for the first time using SEIRAS, that we can control the large-scale reorientation of AMP helices to form the active ion channel form.

Forbrig et al., Langmuir, 2018
Monitoring the orientational changes of alamethicin during incorporation in bilayer lipid membranes.
DOI: 10.1021/acs.langmuir.7b04265

9. An tethered bilayer membrane system Tailored for IR Studies Membrane Proteins

Electrode-interfaced membrane systems are necessary to study and utilize membrane proteins for various biotechnological applications. However, previous IR spectro-electrochemical studies used membrane systems developed for electrochemical approaches. We construct a IR-tailored membrane system and demonstrate its applicability by monitoring the catalytic generation of the proton-motive force by cbo3 oxidase.

Wiebalck & Kozuch et al., J. Phys. Chem. B, 2016
Monitoring the transmembrane proton gradient generated by cytochrome bo3 in tethered bilayer lipid membranes using SEIRA spectroscopy.
DOI: 10.1021/acs.jpcb.6b01435

6. The mitochondrial human voltage-dependent anion channel (HVDAC) acts via deformation Its b-barrel structure

The voltage-dependent anion channel (VDAC) regulates the transfer of metabolites between the cytosol and the mitochondrium. Opening and partial closing of the channel is known to be driven by the transmembrane potentia. Our results indicate alterations of the inclination angle of the β-strands as crucial molecular events, reflecting an expansion or contraction of the β-barrel pore.

Kozuch et al., Phys. Chem. Chem. Phys., 2014
Voltage-dependent structural changes of the membrane-bound anion channel hVDAC1 probed by SEIRA and electrochemical impedance spectroscopy.
DOI: 10.1039/C4CP00167B

3. Lipid-tethered membrane systems on Plasmonic surfaces Enable IR Spectroscopy and Electrochemistry

Tethered membrane systems have been routinely used in electrochemical studies. We construct for the first time a tethered membrane with insulating properties on a plasmonic, nanostructured Au electrode and demonstrate, as proof of concept, the spectroscopic and electrochemical analysis of the ion channel-forming peptide gramicidin A.

Kozuch et al., Angew. Chem. Int. Ed., 2012
Combined electrochemistry and surface-enhanced infrared absorption spectroscopy of gramicidin A incorporated into tethered bilayer lipid membranes.
DOI: 10.1002/anie.201203214