Nuclear magnetic resonance assays

King GF, DJ Richardson, JB Jackson, SJ Ferguson (1987) Dimethyl sulfoxide and trimethylamine-A-oxide as bacterial electron acceptors use of nuclear magnetic resonance to assay and characterise the reductase system in Rhodobacter capsulatus. Arch Microbiol 149 47-51. 

Retention of a protein or protein activity after 105,000y, 1 hr Chromatography on gel filtration columns with large pore sizes Electron microscopy—however, sample preparation may partially reconstitute membranes Decrease in solution turbidity, which may be detected by a diminution in light scattering or an enhancement in light transmission Diffusion of membrane lipids as assayed by nuclear magnetic resonance and electron spin resonance... 

Whenever a higher degree of specificity is mandatory, other techniques have to be employed. A proton nuclear magnetic resonance (PMR) spectroscopic method has been described by Hanna [107] for the direct assay and identifica-... 

Nuclear magnetic resonance (NMR) measurements are usually considered to be slow processes, but recent advances in the design of flow-through NMR cells have allowed the method to be applied in combinatorial chemistry 97). These technological improvements were applied to the development of two NMR-based high-throughput ee assays for evaluating the products of enzyme- or transition metal-catalyzed reactions 98). 

In addition, this procedure was quite tedious and time consuming. Therefore, in recent years when physical methods for assaying molecules in mixtures—methods such as nuclear magnetic resonance (NMR), gas chromatography, and others—have become available, a renaissance in the study of redistribution reactions has taken place. These methods allowed a rapid, quantitative, and precise determination of all of the reaction products present in a mixture. Also, equilibrium reactions could be carried out in much smaller sample sizes, thus permitting the study of exotic, hard-to-obtain compounds. Redistribution reactions—the kinetics as well as the equilibria—can now be measured directly in sealed NMR tubes. Furthermore, the relatively recent widespread availability to chemists of high-speed computers, in addition to these modern analytical tools, has facilitated the use of the appropriate mathematics even when highly complicated. 

SpA, Staphylococcal protein A PpL, protein L from Peptostreptococcus Magnus IgG, immunoglobulin G Gla, y-carboxyglutamic acid SPR, surface plasmon resonance ELISA, enzyme-linked immunosorbent assay FITC, fluorescein isothiocyanate NMR, nuclear magnetic resonance... 

Several experimental methods can be used for the identification or mapping of epitopes. X-ray crystallography, nuclear magnetic resonance, and electron microscopy map the structural epitopes that are in contact with antibody, whereas methods such as PEPSCAN and enzyme-linked immunosorbent assay are functional in approach (6). These experimental approaches, like others, require resources, time, and money. 

In general, however, detailed protocols for the direct analysis of stereochemical features by mass spectrometric means have not been achieved so far. Instead, other analytical methods, such as X-ray analysis or nuclear magnetic resonance (NMR), elegantly address these issues [3]. However, with respect to the analysis of trace compounds and in the context of high-throughput analytical methods, it would be beneficial to develop tools for rapid stereochemical assays by mass spectrometric means or hyphenated techniques [4,5]. 

The demand for enzyme assays that not only monitor overall activity but also en-antioselectivity stimulated the development of further assay systems that are still, however, in a rather experimental state with respect to high-throughput enzyme screening applications. These methods include assays based on electron spin resonance spectroscopy (ESR) [91], nuclear magnetic resonance (NMR) [92,93], IR-thermography [94] or electrospray ionization spectrometry (ESI-MS) [95]. 

Metaferia et al. reported on the synthesis and cytotoxicity of C3 -C4 linked macrocyclic taxoids in 2001. The synthetic strategy was also based on RCM. Similar to Ojima et al. s finding, these compounds (100) are less active than paclitaxel in both cytotoxicity and tubulin assays.However, after careful inspection of the bioactive conformations of taxoids with computer simulation and nuclear magnetic resonance (NMR) experiments, they designed several C-4 and C3 -Ph orf/io-position linked taxoids (101) that were highly active, several times better than paclitaxel. ... 

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