Labeling techniques deuteration

Protein NMR has advanced with the help of stable isotope labeling techniques, which allowed to obtain multinuclear multidimensional spectra. To apply the NMR for large proteins, the control of relaxation time is also important.21,120 For instance, a deuteration for non-exchangeable protons significantly attenuates the relaxation rates. In this case, the amount of NOEs also reduced depending on the deuteration. Therefore, other complementary NMR-derived information will be required (Section 9). 

Uronic acid residues in polysaccharides are reduced to neutral sugars either before or after methylation. If the reduction is performed with a deuterated reductant, the neutral sugar obtained is readily distinguishable by m.s. from the other neutral sugars present in the polysaccharide. This labelling technique has been used in methylation analyses of fungal glucuronoglucans and capsular, bacterial polysaccharides. ... 

Instrumental calibration Labelling techniques and deuteration Sources of X-rays and neutrons... 

Dual-Labeled Technique for Human Lipid Metabolism Studies Involving Deuterated Fatty Acid Isomers 66th Annual Mtg., AOCS, Dallas, Texas... 

At first the labelling technique described above was applied to extract the single particle scattering ctor of PSS solutions (M = 30.(XX) g/mol) with no added salt at different polyion concentrations 16 g/1 Cp < 120 g/1 [134]. These measurements were repeated later [131] because in the first investigation the hydrogenated PSS was not completely matched. The extraction of the single particle scattering factor required measurements at different ratios of deuterated... 

A number of papers have appeared giving a complete description of this technique which is sometimes known in the literature as elastic recoil detection (ERD). The discussion presented here will therefore be brief. FRES is used to determine the volume fraction versus depth profile of a species labelled by deuteration which was allowed to diffuse into an unlabelled host. The diffusion coefficient is extracted from this profile using a solution to the diffusion equation. 

The incorporation of a chapter on deuteration in a steroid monograph is quite reasonable since development of a number of the most important deuteration reactions have actually had their impetus through steroid research. The field of steroid chemistry offers possibly the largest variety of deuteration reactions of any area of organic chemistry. Many of these deuteration techniques have also been used for tritium labeling, which is especially pertinent in view of the large demand for tritiated steroids as tracers in biological experiments. 

It has been reported recently that 17/ -acetoxy-5a,14a-androstan epimerizes at C-14 when photolyzed in cyclohexane solution in the presence of mercuric bromide. When the reaction is carried out in perdeuterated cyclohexane, the product consists of 55 % d - and 12% d2-labeled species. This reaction may develop into an interesting deuteration technique if the incorporated deuterium can be securely assigned to the epimerized position. 

The best insight into the relaxation behavior of star polymers in dilute solution can be expected if, in addition to the whole star system, different parts of the star are considered separately. This can be achieved easily by neutron scattering techniques on systems where not only the entity of arms, but also single arms, the core or shell parts are labelled by proton deuterium exchange. With respect to the core-shell labelling it is convenient to build up the arms as diblock copolymers of A-B type with protonated or deuterated but otherwise chemically identical A and B blocks. 

The power of the system to overcome the problems associated with coeluting compounds is demonstrated in conjunction with the use of deuterated (or13C-labelled compounds) as internal standards. Such techniques could not be used in conventional gas chromatography as the deuterated compounds often co-elute, making quantification difficult if not impossible. With the ion-trap detector, however, it is easily possible to differentiate between the ions arising from the different compounds and the intensities of these ions could then be used for quantification of the compounds involved. The application of such techniques can be shown by... 

Size restrictions are again similar to that encountered in protein NMR up to ca. 20-30 kDa complex size, line widths will usually be acceptable to allow detection of the XH resonances of the labeled or unlabeled component, including NOESY transfer steps. Beyond that, deuteration of the protein component becomes essential to reduce excessive line broadening. For the observation of the (15N-) labeled component (i.e., isotope editing), the use of TROSY techniques will further extend the size limit (Chapt. 10) however, this approach does not work for unlabeled components. 

Fig. 11.8 Equilibrium perturbation trace for deuterated L-malate reaction catalyzed by malic enzyme. The equilibrium perturbation technique is discussed in Section 7.1.4. The label on the ordinate, p,M has been recalculated from the change in absorbance of TPNH at 340 nm (Schimerlik, M. I., Rife, J. E. and Clcland, W. W. Biochemistry 14, 5347 (1975))...

A number of ex situ spectroscopic techniques, multinuclear NMR, IR, EXAFS, UV-vis, have contributed to rationalise the overall mechanism of the copolymerisation as well as specific aspects related to the nature of the unsaturated monomer (ethene, 1-alkenes, vinyl aromatics, cyclic alkenes, allenes). Valuable information on the initiation, propagation and termination steps has been provided by end-group analysis of the polyketone products, by labelling experiments of the catalyst precursors and solvents either with deuterated compounds or with easily identifiable functional groups, by X-ray diffraction analysis of precursors, model compounds and products, and by kinetic and thermodynamic studies of model reactions. The structure of some catalysis resting states and several catalyst deactivation paths have been traced. There is little doubt, however, that the most spectacular mechanistic breakthroughs have been obtained from in situ spectroscopic studies. 

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