Journal of Lipid Research, Vol 23, 161-170, Copyright © 1982 by Lipid Research, Inc.
High resolution nuclear magnetic resonance spectroscopy of bile salts: individual proton assignments for sodium cholate in aqueous solution at 400 MHz
S Barnes and JM Geckle
The 400 MHz 1H-nuclear magnetic resonance spectrum of sodium cholate in
dilute aqueous solution has been successfully resolved using a combination
of decoupling, partial relaxation, and decoupled partial relaxation
techniques. The individual carbon resonances in the 13C-NMR spectrum of
sodium cholate have also have assigned. Assignments of individual methylene
protons were made by consideration of the molecular structure of sodium
cholate and the expected couplings and 1H- nuclear Overhauser enhancement
experiments. Verification of the assignments of the methine protons was
made by application of single frequency 1H-decoupled 13C-NMR. Variation of
pH* from 6.0 to 11.0 did not alter the individual chemical shifts except
for those between 2.12 delta and 2.30 delta, originating from the protons
on the C23 position adjacent to the ionizable carboxyl group. The chemical
shifts of the proton resonances were independent of concentration below 5
mM. Above 10 mM (micellar region), the proton chemical shifts were altered
slightly and some band broadening occurred. These data are consistent with
the formation of small micellar aggregates (up to N = 4) of cholate
molecules.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
