Saffrich, R. and Kalbitzer, Hans Robert and Bodenmüller, H. and Muhn, P. and Pipkorn, R. and Schaller, H. C. (1989) ¹H-nuclear magnetic resonance studies of the neuropeptide head activator. Biochimica et biophysica acta 997 (1-2), pp. 144-153.
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The 1H-NMR spectrum of the neuropeptide head activator in aqueous solution has been completely assigned by two-dimensional NMR spectroscopy and selective deuteration. The apparent pseudo-first-order exchange rate, kex, of the backbone amide protons and the correspondent activation enthalpies, delta H not equal to, were determined. The exchange rates decrease and the activation enthalpies increase from the N-terminal to the C-terminal part of the peptide. The exchange rates vary from 21 to 0.3 s-1 at 274 K, the activation enthalpies from 60 to 75 kJ.mol-1. The pK values of the terminal carboxyl group and of the lysine amino group have been estimated as 3.3 and 10.3, respectively. The NMR results are in line with a dimeric structure in an antisymmetric arrangement of the subunits, forming an antiparallel beta-pleated sheet between C-terminal segments. The peptide bonds between pGlu-1, Pro-2 and Pro-3 are predominantly in trans-configuration, in fact no cis-isomers can be observed spectroscopically. The structure appears to be very stable; in the temperature and pH range studied, i.e., from 274 to 338 K and from pH 0.8 to pH 11.6, there are no spectroscopic indications for a global structural change.
|Institutions:||Biology, Preclinical Medicine > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Dr. Hans Robert Kalbitzer|
|Subjects:||500 Science > 570 Life sciences|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||03 Sep 2010 12:19|
|Last Modified:||03 Sep 2010 12:19|