TrisGlycineSDS

TrisGlycineSDS, commonly referred to as Tris-Glycine-SDS buffer, is a running buffer used in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). It provides the ionic mobility and denaturing conditions necessary for separating proteins primarily by their molecular weight. The presence of SDS denatures proteins and imparts a uniform negative charge, allowing separation to be size-dependent.

The standard composition of TrisGlycineSDS running buffer is 25 millimolar Tris base, 192 millimolar glycine, and 0.1% (w/v) SDS. At this formulation, the pH of the buffer in practice is around 8.3, though pH adjustments may be made during preparation. The SDS concentration is chosen to balance protein denaturation with adequate conductivity and heat management during electrophoresis.

Preparation and use involve dissolving the salts in deionized water, adding SDS, and adjusting the volume and pH as needed before filling the gel apparatus. The buffer is used to fill both the gel running chamber and, in many protocols, the upper reservoir of the gel stack. Gels prepared with this buffer typically run under constant current, with typical voltages scaled to gel thickness and apparatus specifications.

Notes on variants: while 0.1% SDS is common, some protocols use slight deviations (for example, 0.05–0.2% SDS) depending on gel concentration and resolution requirements. TrisGlycineSDS is specifically for denaturing SDS-PAGE; it is not intended for native PAGE, which uses different buffers.