Peptides separation, electrophoretic

Figure 23 Fit of Effective Electrophoretic Mobilities, versus Q (Calculated According to the Relationship t,= q/MIm) for Peptides Separated Using a 50 mM Sodium Phosphate Buffer pH 3.0 324 ab...

With pressurized HP-CEC, the electrophoretic migration rate and the mobile-phase flow rate can be optimized independently for peptide separations. Under such conditions, the retention factor, kof a peptide(s) is dependent on both the electric field and the applied pressure12"1 according to the following ... 

Normally, Jf-casein occurs as a trimer or as a higher oligomer in which the formation of disulfide bonds is probably involved. The protein contains varying amounts of carbohydrates (average values 1% galactose, 1.2% galactosamine, 2.4% N-acetyl neuramic acid) that are bound to the peptide chain through Thr-131, 133, 135 or (in variant A) 136. Jf-Casein is separated electrophoretically into various components that... 

An example of the results obtained in the form of a chromatoelectropherogram can be seen in Figure 9.6. The contour type data display showed the three variables that were studied, namely chromatographic elution time, electrophoretic migration time, and relative absorbance intensity. Peptides were cleanly resolved by using this two-dimensional method. Neither method alone could have separated the analytes under the same conditions. The most notable feature of this early system was that (presumably) all of the sample components from the first dimension were analyzed by the second dimension, which made this a truly comprehensive multidimensional technique. 

McCormick, R. M., Capillary zone electrophoretic separation of peptides and proteins using low pH buffers in modified silica capillaries, Anal. Chem., 60, 2322, 1988. 

Simple etching of the capillary end served to decouple the electrophoretic current from that of amperometric detection, permitting quantitation of attomole levels of catecholamines from brain microdialyzates.24 A postcolumn reactor using bromine generated electrochemically in situ has been used in the detection of peptide thiols, such as glutathione and cysteine, separated by capillary electrophoresis.25... 

Capillary zone electrophoresis, an up-to-date high resolution separation method useful for proteins and peptides, has been shown to be a useful method for determining electrophoretic mobilities and diffusion coefficients of proteins [3], Diffusion coefficients can be measured from peak widths of analyte bands. The validity of the method was demonstrated by measuring the diffusion coefficients for dansylated amino acids and myoglobin. 

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