Publications de Horst Arthur Vogel

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Raman spectra of dihexadecylphosphatidic acid and of dimyristoylphosphatidylcholine and its longer chain homologs were obtained as a function of temp. to study the conformational order of the hydrocarbon chains in lipid bilayers. The frequency of the longitudinal acoustical vibration band is evaluated in terms of the length of all-trans chain segments. In the ordered phase, the chains are found to be overwhelmingly in the all-trans conformation. In the fluid phase, definite all-trans segments occur predomin

Progress in understanding signal transduction and metabolic pathways is hampered by a shortage of suitable sensors for tracking metabolites, second messengers, and neurotransmitters in living cells. Here we introduce a class of rationally designed semisynt ...

Fluorescence Correlation Spectroscopy (FCS) is a suitable technique to investigate biomol. interactions. The advantage of FCS lies in its wide dynamic range in the time and concn. domain, its sensitivity, and thus in the small amt. of material needed. The characteristic time of the processes that can be measured spans more than eleven orders of magnitude, between several nanoseconds up to hours; the measurable concn. range extends from 0.1 nM to several mM. Here we report on FCS expts. to investigate the pr

A symposium report. The total synthesis of melittin-TASP, T4-(4a26) (TASP = template assembled synthetic proteins) is described together with its structural and ion-channel forming properties in planar lipid bilayers. A voltage-dependent channel activity is obsd. upon application of pos. voltage on the side of protein addn. This rectification is indicative of four helixes structurally forced into an unidirectional orientation within the channel aggregate. Melittin-TASPs show a two orders of magnitude higher

The conformation of the polypeptide melittin in lipid membranes as detd. by Raman spectroscopy is a bent a-helix formed by the mainly hydrophobic residues 1-21, and a nonhelical C-terminal segment of the hydrophilic residues 22-26. Fluorescence quenching expts. on tryptophan (Trp)-19 reveal that all C-termini are located on that side of a vesicular membrane to which melittin was added. By fluorescence energy transfer between unmodified and modified Trp-19 residues, melittin is shown to aggregate in membrane

Chem. ligation methods in combination with regioselective addressable templates have allowed the prepn. of well defined complex monomol. films tethered to gold surfaces. The supramol. monolayers exposed artificial recognition sites, here for monoclonal antibodies. SPR, FTIR spectroscopies, and TOF-SIMS were ideally suited surface sensitive techniques to enable the essential control of the individual reaction steps. The concept presented here for the functionalization of gold surfaces may be easily applied t

A highly-sensitive surface fluorescence technique was combined with a powerful method for the oriented reversible immobilization of membrane proteins on oxide surfaces. Affinity and kinetic parameters of the interaction of the receptor and a fluorescent ligand were evaluated. The approach is particularly suited for the study of rapid ligand-receptor interactions where optimized cell volume, flow and injection conditions are required.

A review. The function of biol. important ion channels can be measured in supported lipid membranes by impedance spectroscopy. This approach offers substantial advantages over traditional electrophysiol. measurements. In this article, we present an overvie ...

A general approach for the sequential labeling of fusion proteins of O6-alkylguanine-DNA alkyltransferase (AGT) with different fluorophores in mammalian cells is presented. AGT fusion proteins with different localizations in the cell can be labeled specifically with different fluorophores, and the fluorescence labeling can be used for applications such as multicolor anal. of dynamic processes and fluorescence resonance energy transfer measurements. The facile access to a variety of different AGT substrates

The present invention relates to a method for testing a substance interacting with a target molecule in a cell by fluorescence correlation spectroscopy (FCS) by adding a test substance to the cell and determining a distribution of diffusion coefficients fo ...

We performed lateral force microscopy on thiolipid Langmuir-Blodgett (LB) films physisorbed on mica substrates with a silicon tip of an at. force microscope. The structure of condensed domains, reflecting their sym. morphol., was obsd. The lateral (friction) forces were measured as a function of (normal) applied load, of sliding velocity and of the mol. orientation of these films. At a fixed velocity, lateral force increases with applied load in a linear fashion. Within the velocity range 0.01 to .apprx. 50

The binding of metal ions to self-assembled nitrilotriacetic acid (NTA)-modified thioalkane monolayers was monitored by impedance spectroscopy via a capacitance change of the blocking gold electrode. Binding to a fluorescent NTA-derivative and the native NTA, measured in bulk by fluorescence quenching and isothermal titration calorimetry, was determined for comparison. Surface and bulk absolute dissociation constants K-abs of metal ion-NTA complexes for these three derivatives showed no significant differen

Metal ions, such as Na+, Mg2+, Ca2+, and Zn2+, are highly abundant in biological systems. For many G protein-coupled receptors (GPCRs), metal ions, especially Na+, have been found to stabilize the receptors' inactivate state preventing receptor activation. ...

The std. deviation (SD) in fluorescence correlation spectroscopy (FCS) has been mostly neglected in applications. However, the knowledge of the correct SD is necessary for an accurate data evaluation, esp. when fitting theor. models to exptl. data. In this work, an algorithm is presented that considers the essential features of FCS. It allows prediction of the performance of FCS measurements in various cases, which is important for finding optimal exptl. conditions. The program calcs. the SD of the exptl. a

A new simple concept for a miniaturized monolayer trough is described. The overall monolayer area in the expanded state is approx. 150 mm2 and can be reduced by a factor of 2. The surface area is a function of the shape of the meniscus formed by the subphase and is controlled by the amt. of water in the monolayer trough. The controlled compression of monolayers to a desired area per mol. with simultaneous observation of the lateral distribution of fluorescently labeled mols. is shown. A biol. reaction betwe

A multi-gene family of ~1000 G protein-coupled olfactory receptors (ORs) constitutes the molecular basis of mammalian olfaction. Due to the lack of structural data its remarkable capacity to detect and discriminate thousands of odorants remains poorly unde ...

We show that it is possible to immobilize membrane proteins uniformly and reversibly as self-assembled (sub)monolayers on nitrilotriacetic acid-covered sensor surfaces via hexahistidine sequences present either in the protein or in lipid membranes. Fourier transform IR spectra of such self-assembled (sub)monolayers deliver important structural information of the membrane proteins and are suited to screen the function of cellular receptors. [on SciFinder (R)]

We have expressed the 5-HT3 receptor with two transient expression sytems: the Semliki Forest virus and the HEK293EBNA. Both systems allow the rapid expression of functional receptor protein at very high level: up to 107 receptors per cell. Large scale production yielded 1 to 2 mg of receptor protein per liter. The solubilisation of the receptor from membranes has been optimised; C12E9 solubilised 50 to 60 % of the ligand binding activity. A C-terminally engineered hexahistidine-tag facilited efficient puri

We present a method that allows the on-demand release and mixing of zepto- to femtoliter vols. of solns. in the interior of vesicular nanoreactors. The reactors comprise a nested system of lipid vesicles, part of which release their cargo in the interior of the others during a thermotropic phase transition. The performance of individual reactors immobilized on glass is characterized using confocal microscopy and a fluorescent dye that reports diln. during the release. The results confirm the predicted temp.

The invention relates to a functionalized, polymer-reinforced (sterically stabilized) vesicle which comprises a biol., biochem. or synthetic identifying element for identifying and binding a ligand. In addn., the inventive vesicle optionally contains labels which serve as signal-generating constituents in a bioanal. detection method. The invention also relates to a method for producing said vesicle and to the use thereof in detection methods. Thus, self assembled monolayers (SAMs) were produced on the surfa

Horst Arthur Vogel

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Conformational order of the hydrocarbon chains in lipid bilayers. A Raman spectroscopic study

Semisynthesis of fluorescent metabolite sensors on cell surfaces

Characterization of a transmembrane receptor protein by fluorescence correlation spectroscopy

Chemical synthesis and functional characterization of melittin-TASP molecules

The structure of melittin in membranes

Functional molecular thin films: topological templates for the chemoselective ligation of antigenic peptides to self-assembled monolayers

Waveguide fluorosensor for the detection of ligand-receptor interactions - The 5-HT3 serotonin receptor

Investigating the function of ion channels in tethered lipid membranes by impedance spectroscopy

Labeling of fusion proteins with synthetic fluorophores in live cells

Method for testing a substance interacting with a target molecule

The dependence of friction anisotropies on the molecular organization of LB films as observed by at. force microscopy

Metal ion trace detection by a chelator-modified gold electrode: A comparison of surface to bulk affinity

The role of metal ions in G protein-coupled receptor signalling and drug discovery

The standard deviation in fluorescence correlation spectroscopy

A miniaturized monolayer trough with variable surface area in the square-millimeter range

Exchanging ligand-binding specificity between a pair of mouse olfactory receptor paralogs reveals odorant recognition principles

Controlled Immobilization of Membrane Proteins to Surfaces for Fourier Transform Infrared Investigations

Transient-expression technologies, their application and scale-up: 5-HT3 serotonin receptor case study

Integrated Nanoreactor Systems: Triggering the Release and Mixing of Compounds Inside Single Vesicles

Detection of biomolecules using polymer containing vesicles and functionalized sensors