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Bond Type of bond Specific type of bond Absorption peak (cm −1) Appearance C─H alkyl methyl 1260 strong 1380 weak 2870 medium to strong 2960 medium to strong methylene: 1470 strong 2850 medium to strong 2925 medium to strong methine: 2890 weak vinyl: C═CH 2: 900 strong 2975 medium 3080 medium C═CH 3020 medium monosubstituted alkenes ...
The HSQC experiment is a highly sensitive 2D-NMR experiment and was first described in a 1 H— 15 N system, but is also applicable to other nuclei such as 1 H— 13 C and 1 H— 31 P. The basic scheme of this experiment involves the transfer of magnetization on the proton to the second nucleus, which may be 15 N, 13 C or 31 P, via an INEPT ...
1 H– 15 N HSQC spectrum of a fragment of the protein NleG3-2. Each peak in the spectrum represents a bonded N–H pair, with its two coordinates corresponding to the chemical shifts of each of the H and N atoms. Some of the peaks are labeled with the amino acid residue that gives that signal. [16
With 2-methylpropane, (CH 3) 3 CH, as another example: the CH proton is attached to three identical methyl groups containing a total of 9 identical protons. The C−H signal in the spectrum would be split into 10 peaks according to the n + 1 rule of multiplicity. Below are NMR signals corresponding to several simple multiplets of this type.
Deuterium (hydrogen-2, symbol 2 H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, 1 H. The deuterium nucleus ( deuteron ) contains one proton and one neutron , whereas the far more common 1 H has no neutrons.
Thus, in the 15N-HSQC, with a 15 N labelled protein, one signal is expected for each nitrogen atom in the back bone, with the exception of proline, which has no amide-hydrogen due to the cyclic nature of its backbone. Additional 15N-HSQC signals are contributed by each residue with a nitrogen-hydrogen bond in its side chain (W, N, Q, R, H, K).
By using the information obtained from the integration of a 1 H NMR spectrum, the degree of polymerization (X n) can be calculated. With knowledge of the identity of the end groups/repeat unit and the number of protons contained on each, the X n can then be calculated. For this example above, once the 1H NMR has been integrated and the values ...
The presence or absence of imino proton resonances, or of coupling between 15 N atoms across a hydrogen bond, indicates the presence or absence of basepairing. For large-scale structure, these local parameters must be supplemented with other structural assumptions or models, because errors add up as the double helix is traversed, and unlike ...