Addition of deoxycholate in electroimmunoassay and crossed immunofocusing for quantification of beta 2-glycoprotein I and its subfractions.

Beta 2-Glycoprotein I was shown to be a hydrophilic protein exhibiting no charge shift in the presence of a cationic detergent, but a charge shift in the presence of an anionic detergent. The latter was suggested to be caused by a binding of beta 2-glycoprotein I to deoxycholate in the Triton X-100/deoxycholate micelles. Quantification by electroimmunoassay of asialo-beta 2-glycoprotein I and subfractions of beta 2-glycoprotein I gave different results although identical results were obtained in single radial immunodiffusion. Addition of 0.2% (w/v) of deoxycholate to the agarose gels containing Triton X-100 prior to electrophoresis, however, eliminated these differences. The effect of deoxycholate on the rate of migration of beta 2-glycoprotein I was found applicable for electroimmunoassay of the protein. Crossed immunofocusing of plasma from individual donors, electrophoresed in an agarose containing Triton X-100/deoxycholate micelles confirmed a postulated variation in the relative composition of subfractions of beta 2-glycoprotein I in plasma earlier suggested by Finlayson and Mushinski (Finlayson, J.S. and Mushinski, J.F. (1967) Biochim. Biophys. Acta 147, 413-420).