A proton-NMR study of bilirubin IX\alpha solubilization by cholate micelles: application of nuclear Overhauser effects.

Puranam, Kasturi L and Raghothama, S and Balaram, P (1987) A proton-NMR study of bilirubin IX\alpha solubilization by cholate micelles: application of nuclear Overhauser effects. In: Biochimica et Biophysica Acta, Lipids and Lipid Metabolism, 922 (1). pp. 67-77.

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Abstract

The solubilization of bilirubin IX\alpha (I) in aq. soln. by Na cholate micelles was examd. by 270-MHz 1H NMR spectroscopy. The incorporation of I into the micelles was accompanied by specific shifts of I vinyl and bridgehead protons and the C18 and C19 Me groups of the steroid. The obsd. chem. shifts showed a monotonic concn. dependence suggesting that changes in aggregation size are continuous. Nuclear Overhauser effects (NOE) were shown to be a useful probe or micellization. A 4:1 cholate (II)/I mixt. was investigated by difference NOE spectroscopy. The observation of intermol. NOE between peripheral protons of I and II were diagnostic of spatially proximate groups. Inter-II NOE increased in magnitude upon I incorporation, suggesting closer packing of steroid mols. on solubilization of the pigment. Intramol. NOE obsd. for solubilized I were consistent with a compact intramolecularly H-bonded conformation.

Item Type:	Journal Article
Publication:	Biochimica et Biophysica Acta, Lipids and Lipid Metabolism
Publisher:	Elsevier Science Publishers B.V.
Additional Information:	Copyright belongs to Elsevier Science Publishers B.V.
Keywords:	Bilirubin;Cholate micelle;NMR 1H-;Nuclear Overhauser effect;Bile salt
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Chemical Sciences > Sophisticated Instruments Facility (Continued as NMR Research Centre)
Date Deposited:	06 Mar 2008
Last Modified:	19 Sep 2010 04:43
URI:	http://eprints.iisc.ac.in/id/eprint/13205

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