ABSTRACT

There are two different aspects of analytical biochemistry that can be applied to the characterization of plasma and plasma protein fractions. The €rst is the type of characterization used in the biochemical and biophysical characterization of proteins as practiced in the academic departments of biochemistry and chemistry.* The second is the type of analytical science used for the assay of plasma proteins during the commercial puri€cation and product release. It has been acknowledged that these two areas overlap, but I would posit that assays are developed in basic science departments and then used for biopharmaceutical products. Mass spectrometry is an example that is commonly applied to the characterization of recombinant proteins but infrequently, if at all, in the plasma business.†

Early methods for the characterization of blood plasma were €rst based on electrophoretic methods1-3 as developed by Tiselius.4-8 The development of the electrophoretic analysis of protein is the subject of an excellent review9 by Righetti, which was published in 2005. Tiselius developed moving-boundary or free-boundary electrophoresis, in which colloids such as proteins migrate in free solution. In his original application, Tiselius used optical methods to measure the protein boundaries.10 This technique required substantial protein concentration but could provide information on macromolecular interactions without matrix interference.11 Optical methods are also used to measure the boundaries in analytical ultracentrifugation.12-14 A variation of free-boundary electrophoresis has been used to purify intravenous immunoglobulin (IVIG) from plasma.15