ABSTRACT
Ion-exchange chromatography has been used to isolate three separate forms of Pregnancy-Specific beta 1-Glycoprotein (SP1) from pooled, late-pregnancy human sera. Each of the three components was immunochemically identifiable as SP1, yet distinguishable from each other on the basis of rocket morphology resulting from rocket immunoelectrophoresis (RIE). The elution profile from DEAE Sephacel indicated that each component has an isoelectric point below pH 8.6, but suggested a different charge for each molecular species. Crossed immunoelectrophoresis (XIE) of pooled, late pregnancy serum suggested the presence of each component prior to physico-chemical treatment and showed the components to be characterised by alpha, beta or gamma electrophoretic mobility. The differences in rocket morphology suggested differing affinities for the antiserum, and a difference in molecular size, which was confirmed by gel filtration.
Subject(s)
Pregnancy Proteins/isolation & purification , Pregnancy-Specific beta 1-Glycoproteins/isolation & purification , Chemical Precipitation , Chromatography, Gel , Chromatography, Ion Exchange , Female , Humans , Immunoelectrophoresis, Two-Dimensional , Molecular Weight , Polyethylene Glycols/pharmacology , PregnancyABSTRACT
A method is described for the quantitative estimation of a mixture of whey proteins by spectrophotometric scanning of the stained protein bands following polyacrylamide-gel electrophoresis. The incorporation of beta-lactoglobulin A as an internal standard improves the accuracy of the technique. The method has been used to measure residual native whey proteins in milk after heating. Results are presented for whey protein denaturation in skim-milk after heat treatment at 130 and 140 degrees C for various periods of time.
