As expected, flash vacuum pyrolysis of dichloroglyoxime 13 leads to smooth formation of the well-known cyanogen di-N-oxide 14, which is stable up to -45"C.1131 A special feature of this series is that photoexcitation of 14 (1 = 254 nm) does not lead to the isocyanate 15, but to nitrosyl cyanide 18.I
H(C)CH-COSY and (H)CCH-COSY Experiments for13C-Labeled Proteins in H2O Solution
β Scribed by Kalle Gehring; Irena Ekiel
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 354 KB
- Volume
- 135
- Category
- Article
- ISSN
- 1090-7807
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β¦ Synopsis
We present three experiments which serve to identify carbon and proton sidechain resonances in 13 C-labeled proteins. The first is an improvement on the previously published H(C)CH-COSY experiment and comprises the application of gradients for coherence selection and a reduction in the phase cycle. The second experiment is a new (H)CCH-COSY with two carbon dimensions. The (H)CCH-COSY presents several advantages over the H(C)CH-COSY experiment in terms of better sensitivity, improved resolution and easier identification of amino acid spins systems. The third experiment is a 2D proton-edited (H)C(C)H-COSY that allows suppression of methylene resonances. All three HCCH-COSY experiments show good sensitivity and excellent solvent suppression. The 2D version can be acquired in as little as 45 minutes and the 3D versions acquired overnight. The experiments are demonstrated on a 13 C-labeled sample of the second PDZ domain from human phosphatase PTP1E in H 2 O solution.
π SIMILAR VOLUMES
We have prepared RNAs uniformly 13C-labeled in the ribose ring and with the H3',H4',H5'/H5" protons specifically replaced with deuterons (3',4',5'/5"-2H-13C, termed d4-13C ribose), which offers the advantage of spectral simplification without sacrifice of sensitivity for the remaining protons. A 3D