Electrophoresis is a technique which separates charged biomolecules based on the rate at which they migrate in an applied electrical field. In many cases, electrophoreses of proteins are performed using polyacrylamide gel electrophoresis (PAGE)¹⁾. For molecular weight estimation and purity determination of proteins, sodium dodecyl sulfate (SDS)-PAGE is commonly used. SDS is a strongly anionic detergent and is added to samples, gels, and electrodes buffer solutions. SDS denatures and binds to proteins. When used in conjunction with reducing reagents such as 2-mercaptoethanol, dithiothreitol etc. to cleave disulfide bonds, the amount of SDS bound is almost always proportional to the molecular weight of the polypeptide. Therefore, the migration of the denatured polypeptide is independent of its sequence.
Laemmli’s method is the most widely used system of SDS-PAGE²⁾. In this method, the separation and the stacking gel contain Tris-HCl and the upper and lower buffer reservoirs contain Tris-glycine. All components of the system contain SDS. The advantage of Laemmli’s method is that it gives sharper bands in the final plate.¹⁾

[SDS-PAGE according to the method of Laemmli.]

Marker proteins run on 7.5% gel and visualized with Ag-staining.

Lane 1： 250 ng
Lane 2： 62.5 ng
Lane 3： 16 ng
Lane 4： 4 ng
Lane 5： 0 ng

M1948	A2097	A1132
A2098	B3195	B3193
B3194	D3647	G0316
G0317	M0506	T2515
S0588	T2516