ISSN:
1573-904X
Keywords:
13C-edited
;
NMR
;
retinol
;
retinoic acid
;
β-lactoglobulin
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Purpose. Vitamin A (retinol) and its metabolites comprise the natural retinoids. While the biological action of these molecules are thought to be primarily mediated by ca. 55 kDa nuclear retinoic acid receptors, a number of structurally similar 15-20 kDa proteins are involved in the transport, and possibly metabolism, of these compounds. The milk protein β-lactoglobulin B (β-LG) is an 18 kDa protein which binds retinol and may be involved in oral delivery of retinol to neonates. β-LG also binds drugs and other natural products and is of potential interest as a protective delivery vehicle. Methods. To examine the conformation of the model retinoid β-ionone both in solution and when bound to β-LG, NMR and computational methods have been employed. Results. Taken together, NMR studies of β-ionone in solution measuring scalar and dipolar coupling, as well as CHARMm calculations, suggest β-ionone prefers a slightly twisted 6-s-cis conformation. Isotope-edited NMR studies of l3C-labeled β-ionones bound to β-LG, primarily employing the HMQC-NOE experiment, suggest β-ionone also binds to β-LG in its 6-s-cis conformation. Conclusions. The methods employed here allow estimates of protein-bound ligand conformation. However, additional sites of ligand labeling will be necessary to aid in binding site localization.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1018860221492
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