|Title||Effects of desialylation on human α1-acid glycoprotein-ligand interactions.|
|Publication Type||Journal Article|
|Year of Publication||2013|
|Authors||Huang, RY-C, Hudgens, JW|
|Date Published||2013 Oct 8|
|Keywords||Deuterium Exchange Measurement, Glycosylation, Humans, Ligands, Mass Spectrometry, N-Acetylneuraminic Acid, Orosomucoid, Progesterone, Propranolol, Protein Conformation|
Human α1-acid glycoprotein (AGP), an acute-phase glycoprotein, exists predominantly in blood. With its ability to bind basic, lipophilic, and acidic drugs, AGP has served as a drug carrier. It has been shown that the carbohydrate composition of AGP changes in response to tissue injury, inflammation, or infection and can have a great impact on AGP's drug binding activities. The molecular-level details of the effects of desialylation on the AGP conformation and AGP-ligand interactions, however, are unknown. Here we report the use of hydrogen-deuterium exchange coupled with mass spectrometry (HDX-MS) to reveal the changes in AGP conformational dynamics induced by the removal of terminal sialic acid. HDX-MS also reveals the changes in the conformational dynamics of sialylated and unsialylated AGP upon formation of complexes of holo-AGP with progesterone or propranolol. Our HDX-MS results demonstrate that desialylation stabilizes two loop regions that are exterior to the β-sheet barrel in AGP, and this stabilization minimizes the conformational changes of AGP upon binding with progesterone or propranolol.