Infrared Membrane Spectroscopy

Fringeli, U. P.; Günthard, Hs. H.

doi:10.1007/978-3-642-81537-9_6

Cited by 317 publications

(320 citation statements)

References 101 publications

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“…Sample Preparation-Thin films of oriented multilayers were obtained by slowly evaporating the sample on one side of the ATR plate under a stream of nitrogen (22). The ATR plate was then sealed in a universal sample holder.…”

Section: Methodsmentioning

confidence: 99%

Phosphorylation-induced Conformational Changes of Cystic Fibrosis Transmembrane Conductance Regulator Monitored by Attenuated Total Reflection-Fourier Transform IR Spectroscopy and Fluorescence Spectroscopy

Grimard

Ramjeesingh

et al. 2004

Journal of Biological Chemistry

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Cystic fibrosis transmembrane conductance regulator (CFTR) is a member of the ABC protein superfamily. Phosphorylation of a regulatory domain of this protein is a prerequisite for activity. We analyzed the effect of protein kinase A (PKA) phosphorylation on the structure of purified and reconstituted CFTR protein. 1 H/ 2 H exchange monitored by attenuated total reflection Fourier transform IR spectroscopy demonstrates that CFTR is highly accessible to aqueous medium. Phosphorylation of the regulatory (R) domain by PKA further increases this accessibility. More specifically, fluorescence quenching of cytosolic tryptophan residues revealed that the accessibility of the cytoplasmic part of the protein is modified by phosphorylation. Moreover, the combination of polarized IR spectroscopy with 1 H/ 2 H exchange suggested an increase of the accessibility of the transmembrane domains of CFTR. This suggests that CFTR phosphorylation can induce a large conformational change that could correspond either to a displacement of the R domain or to long range conformational changes transmitted from the phosphorylation sites to the nucleotide binding domains and the transmembrane segments. Such structural changes may provide better access for the solutes to the nucleotide binding domains and the ion binding site.Cystic fibrosis is caused by a mutation in the membrane chloride channel CFTR 1 (1). CFTR is a member of the ABC superfamily. As the other members of this family, CFTR contains two transmembrane domains and two nucleotide binding domains (NBD) responsible for ATP hydrolysis. In addition to the common ABC structure, CFTR possesses an R domain (regulatory domain) that contains several consensus phosphorylation sites. Phosphorylation of this domain followed by ATP binding and hydrolysis by the NBDs is necessary to induce chloride permeability (2, 3). Yet, an alternative activation mode has been proposed recently, where glutamate induces chloride channel activity in the absence of PKA and ATP (4), but it still needs further investigation.CFTR contains 10 dibasic (R(R/K)X(S/T)) consensus sequences for PKA phosphorylation as well as several monobasic and low affinity sites, most of them located in the R domain (1). Although the overall sequence identity of CFTR R domains is low, the phosphorylation sites are remarkably conserved among species (5). It is believed that the R domain combines both inhibitory and stimulatory effects. Effectively, deletion of the residues 708 -835 from the R domain (6, 7), and even of the residues 760 -783 (8), generates constitutively active channels. Moreover, overexpression or addition of the unphosphorylated R domain, encompassing residues 590 -858, inhibits chloride transport (9). PKA phosphorylation relieves this inhibition. On the other hand, it has been shown that exogenous phosphorylated R domain (either residues 590 -858, 645-834, or 708 -831) increases the open probability of a CFTR channel construct missing residues 708 -835 from the R domain (7,10,11).Nevertheless, the effect of the ph...

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Section: Methodsmentioning

confidence: 99%

Phosphorylation-induced Conformational Changes of Cystic Fibrosis Transmembrane Conductance Regulator Monitored by Attenuated Total Reflection-Fourier Transform IR Spectroscopy and Fluorescence Spectroscopy

Grimard

Ramjeesingh

et al. 2004

Journal of Biological Chemistry

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“…Orientation of the Secondary Structure-ATR-FTIR spectroscopy provides information on the orientation of the peptide secondary structure embedded in the hydrated lipid film where the lipid acyl chains are oriented perpendicular to the surface of the ATR plate (27). The protein spectra were recorded with parallel and perpendicular polarized light with respect to the plane of incidence, averaging 512 scans at a resolution of 2 cm…”

Section: Methodsmentioning

confidence: 99%

Structure and Orientation of Two Voltage-dependent Anion-selective Channel Isoforms

Abrecht

Goormaghtigh²,

Ruysschaert³

et al. 2000

Journal of Biological Chemistry

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Two VDAC (voltage-dependent anion-selective channel) isoforms were purified from seed cotyledons of Phaseolus vulgaris by chromatofocusing chromatography. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy was used to study the structural properties of the two isoforms reconstituted in a mixture of asolectin and 5% stigmasterol. The IR spectra of the two VDAC isoforms were highly similar indicating 50 to 53% anti-parallel ␤-sheet. The orientation of the ␤-strands relative to the barrel axis was calculated from the experimentally obtained dichroic ratios of the amide I ␤-sheet component and the amide II band. Comparing the IR spectra of the reconstituted VDAC isoforms with the IR spectra of the bacterial porin OmpF, for which a high resolution structure is available, provided evidence for a general structural organization of the VDAC isoforms similar to that of bacterial porins. Hydrogen-deuterium exchange measurements indicated that the exchange of the amide protons occurs to a higher extent in the two VDAC isoforms than in the OmpF porin.Mitochondria are surrounded by two distinct membranes. The mitochondrial outer membrane is freely permeable for small hydrophilic solutes up to approximately 6 kDa. This property has been attributed to the presence of a pore forming protein, the voltage-dependent anion-selective channel (VDAC) 1 or mitochondrial porin (1). Biophysical properties of VDAC channels inserted in planar lipid bilayers have been studied in a large variety of organisms. VDAC channels switch from a high conducting fully open state (3.6 to 4.5 nS in 1 M KCl) at low voltages to several low-conducting substates upon application of voltages higher than Ϯ20 mV. VDAC is slightly anion selective in the fully open state but switches to cation selectivity in the low-conducting substates (2). In these substates, the flow of negatively charged metabolites such as succinate, citrate, phosphate (3), and adenine nucleotides (4, 5) through the channel is strongly reduced compared with the fully open state. Therefore, VDAC is thought to regulate the mitochondrial metabolism by regulating the flux of metabolites across the mitochondrial outer membrane.VDAC channels are involved in different cellular events like the induced release of cytochrome c, which constitutes an early step in apoptosis (6). VDAC is the binding site for cytoplasmic enzymes like glycerol kinase and hexokinase (7) and for the cytoskeleton (8). The different VDAC isoforms that exist in yeast, plants, and mammals could be involved in specific functions. Two human VDAC isoforms have different binding affinities for hexokinase (9). Plant VDAC isoforms have slightly different electrophysiological properties (10), and mitochondria isolated from yeast vdac minus mutants show differences in their outer membrane permeability to NADH depending on which of the three mouse VDAC isoforms was expressed (11). Therefore, it seems reasonable to assume that the multitude of functional properties that are attributed to VDAC could arise from ...

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“…Determination of the structure of molecules adsorbed on electrode surfaces requires a use of spectroscopic and/or microscopic methods combined with electrochemical techniques. Among spectroscopic techniques, infrared spectroscopy (IRS) belongs to one of the most powerful bioanalytical techniques for studies of the molecular structure of biomolecules [12][13][14][15]. It gives the unique opportunity to analyze simultaneously each kind of organic species present in an assembly adsorbed on the electrode surface.…”

Section: Introductionmentioning

confidence: 99%

Application of Polarization Modulation Infrared Reflection Absorption Spectrosocpy Under Electrochemical Control for Structural Studies of Biomimetic Assemblies

Brand

2015

Zeitschrift Für Physikalische Chemie

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An ideal bioanalytical method would allow carrying out sensitive, selective, reproducible, fast, and in situ chemical measurements of the composition, structure and function of complex biological systems. Physical chemistry possesses advanced structure analyzing techniques which are suitable to solve, at a sub-molecular level, the structure of biomolecules. However, the prerequisite of the presence of the electrolyte solution limits the number of applicable structure analyzing techniques. Infrared spectroscopy is one of the most powerful analytical techniques used to identify the structure of biomolecules, monitor structural changes under various experimental environments and physical states. In addition, infrared reflection absorption spectroscopy (IRRAS) has been successfully applied to study supramolecular films at the solid|liquid interface. Assemblies of biomolecules belong to a particularly demanding because they bring specific for the maintenance of their functions experimental requirements which have to be taken into account planning in situ spectroelectrochemical experiments. In this paper potnential of in situ IRRAS under electrochemical control for studies of structural changes in assemblies of biomolecules such as lipid bilayers and protein films is described. Studies of different classes of biomolecules bring certain experimetnal conditions concerning the electrolyte composition, pH value, temperature or chemical nature of the solid support, which have to be fulfilled. Obviously, these conditons may significantly restrict the applicability of the in situ PM IRRAS. The selection of the solid substrate with required optical and electrical properties, the optical window and the electrolyte composition have to be adapted to the needs of biomolecules. Adjustement of experimetnal conditions as well as possibilites of the enlargement of the in situ PM IRRAS for studies of biomimetic assemblies is reviewed in this paper. Furthermore, experimetnal resutls reporting potenial driven changes in models of cell membranes and protein films are reviewed. Pioneering studies aiminig at the determination of structural changes in lipid membranes exposed to physiological electric fields and interacting simultaneously with protiens are described.

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Infrared Membrane Spectroscopy

Cited by 317 publications

References 101 publications

Phosphorylation-induced Conformational Changes of Cystic Fibrosis Transmembrane Conductance Regulator Monitored by Attenuated Total Reflection-Fourier Transform IR Spectroscopy and Fluorescence Spectroscopy

Phosphorylation-induced Conformational Changes of Cystic Fibrosis Transmembrane Conductance Regulator Monitored by Attenuated Total Reflection-Fourier Transform IR Spectroscopy and Fluorescence Spectroscopy

Structure and Orientation of Two Voltage-dependent Anion-selective Channel Isoforms

Application of Polarization Modulation Infrared Reflection Absorption Spectrosocpy Under Electrochemical Control for Structural Studies of Biomimetic Assemblies

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