Dual spin probe

B1.13.4.1 SMALL MOLECULES THE DUAL SPIN PROBE TECHNIQUE... 

Another application of the knowledge of is to employ it for the interpretation of another relaxation measurement in the same system, an approach referred to as the dual spin probe teclmique. A rather old, but... 

Dual spin probe experiments quadrupolar coupling constants Dual spin probe (DSP) techniques [20] are based on the correlation of relaxation data of two different nuclei, allowing for the determination of quadrupolar coupling constants. In cases where these coupling constants exist, the nuclei under investigation are within the same molecule or aggregate. 

Carper, W. R., Pflug, J. L., and Wilkes, J. S., Dual spin probe NMR relaxation studies of ionic structure in l-ethyl-3-methylimidazolium chloride-AlClg molten-salts, Inorg. Chim. Acta, 202,89,1992. 

Busse determined the Co relaxation rates of [Co(acac)3] in several solvents by using the dual spin probe technique. Busse and Abbott conclude that the relaxation rate for cobalt in such an ostoisibly symmetrical com dex can be explained by small djmamic distortion from ideal symmetry that fluctuate owing to rotational reorientation in QD, CE>3COCI>3, and diglyme. If the relaxation is through the rotational reorientation, the relaxation rate, l/Ti, is given by... 

Wagner S, Dinesen TRJ, Rayner T, Bryant RG (1999) High-resolution magnetic relaxation dispersion measurements of solute spin probes using a dual-magnet system. J Magn Reson 140 172-178... 

Very fast electron transfers from P+ to bacteriochlorophyl (Bchl) and from (Bchl)- to QA do not depend on media dynamics and occur via conformationally non-equilibrium states (Fig.3.18). The dual fluorophore-nitroxide molecules (D-A) are also convenient objects for analysing the activity-dynamics relationship. The marked irreversible photoreduction of the nitroxide fragment of the dual probe incorporated into the binding site of HSA only took place when the nanosecond dynamical processes around the probe traced by ESR and fluorescence methods were detected (Rubtsova et al., 1993, Fogel et al, 1994 Likhtenshtein, 1986 Lozinsky et al., 2002). Similar results were reported for another model protein system, i.e. a-chymotrypsin with spin labeled methionin-92 groups (Belonogova et al., 1997). In the latter enzyme, the excited tryptophan group serves as an electron donor. 

HMQC spectra using H as the detector (/) spin can be recorded on a conventional two-chaimel NMR spectrometer with a normal broad band, or selective dual, probe head. However, better signal-to-noise will be achieved using an inverse probe head due to the better filling factor. 

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