Ratio determination of plasma wild-type and L159R apoA-I using mass spectrometry: tools for studying apoA-IFin

Autor: John S. Owen, Manish S. Bharadwaj, Michael J. Thomas, Shaila Bhat, Michael P. Samuel, Mary G. Sorci-Thomas
Jazyk: angličtina
Rok vydání: 2007
Předmět:
Zdroj: Journal of Lipid Research, Vol 48, Iss 1, Pp 226-234 (2007)
Druh dokumentu: article
ISSN: 0022-2275
DOI: 10.1194/jlr.D600031-JLR200
Popis: In this report, methods are described to isolate milligram quantities of a mutant apolipoprotein A-I (apoA-I) protein for use in structure-function studies. Expression of the L159R apoA-I mutation in humans reduces the concentration of plasma wild-type apoA-I, thus displaying a dominant negative phenotype in vivo. Earlier attempts to express and isolate this mutant protein resulted in extensive degradation and protein misfolding. Using an Escherichia coli expression system used predominantly for the isolation of soluble apoA-I mutant proteins, we describe the expression and purification of L159R apoA-I (apoA-IFin) from inclusion bodies. In addition, we describe a mass spectrometric method for measuring the L159R-to-wild-type apoA-I ratio in a 1 μl plasma sample. These new methods will facilitate further studies into the mechanism behind the dominant negative phenotype associated with the expression of the L159R apoA-I protein in humans.
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