Selective interface detection: mapping binding site contacts in membrane proteins by NMR spectroscopy.

Intermolecular contact surfaces are important regions where specific interactions mediate biological function. We introduce a new magic angle spinning solid state NMR technique, dubbed "selective interface detection spectroscopy" (SIDY). In this technique, 13C-attached protons (1Hlig) are dephased by 1H-13C REDOR.

Solid-state NMR analysis of ligand--receptor interactions reveals an induced misfit in the binding site of isorhodopsin.

Rhodopsin is the photosensitive protein of the rod photoreceptor in the vertebrate retina and is a paradigm for the superfamily of G-protein-coupled receptors (GPCRs). Natural rhodopsin contains an 11-cis-retinylidene chromophore. We have prepared the 9-cis analogue isorhodopsin in a natural membrane environment using uniformly (13)C-enriched 9-cis retinal.

Accurate CSA measurements from uniformly isotopically labeled biomolecules at high magnetic field.

Obtaining chemical shift anisotropy (CSA) principal values from large biomolecular systems is often a laborious process of preparing many singly isotopically labeled samples and performing multiple independent CSA measurements. We present CSA tensor principal values measured in the biomolecular building blocks tyrosine.HCl, histidine.

Extraction of carotenoids from feces, enabling the bioavailability of beta-carotene to be studied in Indonesian children.

Previously, we have presented a method for quantifying beta-carotene bioavailability based on analysis in serum, following administration of (13)C-labeled beta-carotene. Because stool samples can be collected noninvasively, we have now extended the method to measure the bioavailability based on measurements in feces. An extraction method was developed to enable measurement of concentrations and degree of isotopic enrichment of retinol, retinyl palmitate and carotenoids in feces.

(1)H and (13)C MAS NMR evidence for pronounced ligand-protein interactions involving the ionone ring of the retinylidene chromophore in rhodopsin.

Rhodopsin is a member of the superfamily of G-protein-coupled receptors. This seven alpha-helix transmembrane protein is the visual pigment of the vertebrate rod photoreceptor cells that mediate dim light vision. In the active binding site of this protein the ligand or chromophore, 11-cis-retinal, is covalently bound via a protonated Schiff base to lysine residue 296.

The preparation of all-trans uniformly (13)C-labeled retinal via a modular total organic synthetic strategy. emerging central contribution of organic synthesis toward the structure and function study with atomic resolution in protein research.

Uniformly [(13)C(20)]-labeled all-trans-retinal (1) has been prepared via a convergent modular total organic strategy with high isotope incorporation (>99%) and without isotope dilution starting from commercially available 99% enriched (13)C-labeled starting materials. For this purpose we have developed a strategy that is based on four different modules: [1,2,3,4,(3-CH(3))-(13)C(5)]-4-(diethylphosphono)-3-methyl-2-butenenitrile (3), [1,2,3,4-(13)C(4)]-ethyl acetoacetate (7), [U-(13)C(5)]-4-bromo-2-methyl-2-butene (13), and [U-(13)C(10)]-2,6,6-trimethylcyclohex-2-ene-1-ylcarbonitrile (16). This scheme permits the synthesis of the full cassette of all isotopomers with (13)C-labels at any position or combination of positions by using different (13)C-labeled starting materials.