A 1H-NMR study of bilirubin IXα solubilization by cholate micelles: application of nuclear Overhauser effects

Purana, Kasturi Lahiri ; Raghothama, S. ; Balaram, P. (1987) A 1H-NMR study of bilirubin IXα solubilization by cholate micelles: application of nuclear Overhauser effects Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 922 (1). pp. 67-77. ISSN 0005-2760

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/000527...

Related URL: http://dx.doi.org/10.1016/0005-2760(87)90246-3

Abstract

The solubilization of bilirubin IXα in aqueous solution by sodium cholate micelles has been examined by 270 MHz 1H-NMR spectroscopy. Incorporation of bilirubin into the micelles is accompanied by specific shifts of bilirubin vinyl and bridgehead protons and the C18 and C19 methyl groups of the steroid. The observed chemical shifts show a monotonic concentration dependence suggesting that changes in aggregation size are continuous. Nuclear Overhauser effects (NOE) have been shown to be a useful probe or micellization. A 4:1 cholate/bilirubin mixture has been investigated by difference NOE spectroscopy. The observation of intermolecular nuclear Overhauser effects between peripheral protons of bilirubin and cholate are diagnostic of spatially proximate groups. Inter-cholate nuclear Overhauser effects increase in magnitude upon bilirubin incorporation suggesting closer packing of steroid molecules on solubilization of the pigment. Intramolecular nuclear Overhauser effects observed for solubilized bilirubin are consistent with a compact intramolecularly hydrogen-bonded conformation resembling that determined for bilirubin in the solid state.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Bilirubin; Cholate Micelle; NMR; 1H-; Nuclear Overhauser Effect; Bile Salt
ID Code:4743
Deposited On:18 Oct 2010 06:53
Last Modified:16 May 2011 07:04

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