Microheterogeneity of proteins

At present neither of these two procedures is perfectly fitted for the determination of the isoelectric points of proteins, but they are quite suitable in the investigation of the microheterogeneity of proteins, as we shall see below. 

Schachter H (1986) Biosynthetic controls that determine the branching and microheterogeneity of protein-bound oligosaccharides. Biochem Cell Biol 64 163-181... 

Proteins are important not only for their function but also for their diagnostic significance. Proteins maintain structural integrity and perform different functions such as catalytic, hormonal, or receptors. The function of many of the proteins of clinical interest remains not well understood nevertheless these proteins remain to be important. The CE is useful for quantification, purity check, and detection of microheterogeneity of proteins. 

In 1954 Colvin, Smith, and Cook advanced the concept of microheterogeneity of proteins. They concluded that a native protein should be described as a population of closely related individiuals which may differ either discretely or continuously in a number of properties and cited plasma albumin as an example. 

Hiraoka, A., et al (1998). Sodium dodecyl sulfate-capillary gel electrophoretic analysis of molecular mass microheterogeneity of beta-trace protein in cerebrospinal fluid from patients with central nervous system diseases./. Chromatogr. A 802, 143-8. 

Hiraoka, A., et al (2001). Charge microheterogeneity of the beta-trace proteins... 

Fig. 3. Amino acid sequence of several somatic human histone HI proteins to illustrate the microheterogeneity of linker histones. The sequences for human histone HI variants (H1.1-H1.4) were obtained from Ref [373] and Hl-5 was from Ref [412]. The nomenclature followed for the designation of these histone variants was Doenecke (e.g., see Ref. [412]). The nomenclature of Parseghian et at. [373] is shown in parentheses. The regions corresponding to the trypsin-resistant (winged helix motif [96]) which is characteristic of the protein members of the histone HI family are indicated by a boxed inset.

FIGURE 4 Microheterogeneity of a human monoclonal antibody determined by isoelectric focusing. Lane I, marker proteins lane 2, purified antibody and lanes 3-8, separated isoproteins according to the method of Kaltenbrunner et o/.,l... 

BJ Compton. Electrophoretic mobility modeling of proteins in free zone capillary electrophoresis and its application to monoclonal antibody microheterogeneity analysis. J Chromatography 559 357-366, 1991. 

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