Electrophoresis matrix molecular weight

Extensive results have been obtained on the electrophoretic mobility of larger rigid probes, notably polystyrene spheres, in polymer solutions(35-37). Limited measurements find that electrophoresis with a polymer solution as a support medium gives excellent separations of intact bacteria(38). The following are representative results, ordered approximately by increasing matrix molecular weight. 

At fixed polymer concentration, p/fio decreases with increasing matrix molecular weight. Rodbard and Chrambach found that p is not independent of M, consistent with many other results on probe electrophoresis and sedimentation. Nonlinear (in E) mobility behavior was observed, namely the probe mobility increased at larger applied fields. The nonlinearity was more pronounced at larger polymer concentrations. The dependence of p upon E could be said to be shear thinning, but if so the relevant shear rate (for example, involving a thin layer around each probe) must be quite large, because direct measurement at lower shear rates found no dependence of the macroscopic on /c. 

Capillary SDS-Sieving Electrophoresis In the presence of a sieving matrix, mobility decreases monotonically with molecular weight for SDS-complexed proteins. This relationship is the basis of SDS-PAGE separation of proteins. 

Fossil glycoproteins of the soluble organic matrix are present in an 80-million year old mollusc shell from the Late Cretaceous Period. Discrete molecular weight components, as determined by gel electrophoresis, are preserved. A particular repeating amino acid sequence (—Asp—Y—) found in contemporary mollusc shell proteins was identified in fossil glycoproteins425. ... 

During gel electrophoresis, the migration of macromolecules is obstructed by the polymer matrix, and thus depends on the molecular weight as well as the frictional coefficient with the matrix. In the reptation model, DNA is assumed to move in a worm-like fashion through virtual tubes in the gel polymer matrix (Fig. 9.1A). The central result is that the electrophoretic mobility depends on the mean-square end-to-end distance of the macromolecule, and inversely on length (L) or molecular weight. The electrophoretic mobility is expressed as... 

In electrophoresis, protein variants are separated due to differences in their mobility in the presence of an electrical field. Traditionally, electrophoresis has been performed using a stationary slab gel. The most common electrophoretic technique is sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In this technique, a polyacrylamide gel provides a sieving matrix for the protein solution. The protein is mixed with an SDS solution prior to loading onto the gel. By coating the protein with SDS, the charge to mass ratio becomes uniform between proteins. This allows proteins to be separated solely on molecular weight in the presence of the electrical field. The protein/SDS solution is loaded onto the gel which is... 

Alternatively, one can separate the proteins before breaking them into peptides and then subject them to protein breakdown to obtain the peptide. This approach involves mainly the use of gel-based procedures such as one-dimensional or two-dimensional electrophoresis (2-DE) to resolve protein mixture into protein spots based on molecular weight and charge (isoelectric point or pi). Following separation, protein spots are cut out from the gel protein is harvested from gel matrix, digested by peptides, and subjected for further mass spectrometric analysis. 

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