✍ Scribed by M. Hricovíni; M. Guerrini; G. Torri; S. Piani; F. Ungarelli
No coin nor oath required. For personal study only.
JH and 13C NMR relaxation measurements at various magnetic fields have been used to characterize the nature of overall and internal motions in heparin epoxide in aqueous solution. A two-dimensional homonuclear NOESY experiment showed a considerable number of cross-relaxing protons in the molecule. The inter-proton distances calculated from NOE data were compared with those obtained by molecular mechanics calculations. Several discrepancies between the experimental and the theoretical inter-proton distances as well as the variations in ~3C spin-lattice relaxation times, measured at two magnetic fields, indicated that the polysaccharide tumbles anisotropically in solution. The rates of overall and internal motions as well as the order parameters have been calculated using a model-free spectral density function. The numerical values indicate that the correlation times which characterize overall molecular motion are outside the extreme narrowing limit (7'11 = 8 )< l0 -10 S and 7"± = 4.2 × 10 -8 s) and that internal motion correlation time is on a picosecond timescale.
📜 SIMILAR VOLUMES
## Abstract Proton NMR measurements were performed and ^1^H^1^H dipolar interaction energies were measured to delineate the conformation of imipramine in solution. Self‐association of imipramine into dimers was observed and a dimerization constant of 121 mol^−1^ was calculated. The motional correl
## Abstract CD and nmr studies have been carried out on aqueous trifluoroethanol (TFE) solutions of bradykinin (BK) and a bradykinin antagonist. The CD results exhibit a striking effect of TFE on the spectra of BK, with sequence Arg‐Pro‐Pro‐Gly‐Phe‐Ser‐Pro‐Phe‐Arg, and the BK antagonist, with seque
## Abstract The 270 MHz ^1^H and 22.6 MHz ^13^C NMR spectra of DL‐phosphothreonine in D~2~O have been measured and analysed as a function of pD. The __trans__‐__trans__ conformation of the fragment H‐αC‐αC‐βOP predominates at all pD values. The C‐β—O __gauche__ contribution is notably larger fo
The usefulness of 'H bi-selective relaxation times ( 2 ' : ' ) and selective relaxation times (T,') for structure and conformation determination is emphasized. A pulse sequence has been devised which provides the apparent observed T : ' . The cross-relaxations (q,) or Fi, values are derived from the