Separation of Proteins by HPCE

6 ANALYSIS OF PROTEINS IN FORENSICS 8.6.1 Separation of Proteins by HPCE 

Detailed discussion of the use of HPCE for separation of proteins are available in specialized reviews (Karger, 1989 Rohlicek and Deyl, 1989 Steuer et al., 1990 Mazzeo and Krull, 1991 Deyl et al., 1994a, 1994b Li, 1994). 

Protein in untreated capillaries tend to stick to the inner capillary walls. Several approaches have been used to abolish or at least minimize this problem (McCormick, 1988 Bushey and Jorgenson, 1989 Green and Jorgenson, 1989 Emmer et al., 1991 Kajiwara, 1991). The easiest approach is to perform the separations at very high or very low pH values. In the former case, dissociation of the free amino groups is suppressed and, consequently, interactions between the dissociated silanol groups of the capillary surface and the free amino groups of the protein are minimized. At extremely acid pH, the opposite 

In using this approach to prevent sticking, the problem of coating stability must be considered. Therefore the procedure referred to as dynamic coating was introduced (Wu and Regnier, 1991). A number of commercially available coated capillaries are currently marketed. 

Protein sorption to the capillary wall is not an issue with gel-filled capillaries because the wall is shielded by the gel filling. Gel-filled capillaries can be either prepared in the lab or purchased. An easy and inexpensive approach is the dynamic filling of the capillary with a diluted gel solution (typically 4% linear polyacrylamide) (Wu and Regnier, 1992). 

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