The ratio VS/VM is referred to as the volumetric phase ratio, b. Hence:

#Id: 2495

#Unit 13. Methods in Biology

The relationship between acrylamide gel concentration and protein fractionation range

#Id: 2496

#Unit 13. Methods in Biology

.In the Native (Buffer) Gels electrophoresis SDS is absent, and the proteins are not denatured prior to loading. Since all the proteins in the sample being analyzed carry their native charge at the pH of the gel (normally pH 8.7), proteins separate according to their different electrophoretic mobilities and the sieving effects of the gel.

#Id: 2497

#Unit 13. Methods in Biology

In the Native (Buffer) Gels electrophoresis it not possible to predict the behavior of a given protein in a buffer gel, but, because of the range of different charges and sizes of proteins in a given protein mixture, good resolution is achieved.

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#Unit 13. Methods in Biology

Gradient Gels electrophoresis are performed using gradient of  acrylamide Concentration that varies uniformly from, typically, 5% at the top of the gel to 25% acrylamide at the bottom of the gel.

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#Unit 13. Methods in Biology

There are two major advantages to running gradient gels. 

First, a much greater range of protein Mr values can be separated than on a fixed- percentage gel.

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#Unit 13. Methods in Biology

The second advantage of gradient gels is that proteins with very similar M r values may be resolved.