What is the outcome of high molecular weight proteins during SDS-PAGE?

In the context of SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis), high molecular weight proteins tend to remain at the top of the gel. This phenomenon occurs because larger proteins have a more substantial mass that hinders their movement through the gel matrix, which is made up of a network of polyacrylamide. When an electric current is applied, proteins migrate towards the positive electrode, but those with higher molecular weight encounter more resistance due to their size. As a result, they do not travel as far as smaller proteins during the electrophoresis process.

While it's true that high molecular weight proteins can also be denatured by SDS, their movement through the gel is primarily restricted by their size-related interaction with the gel matrix rather than any lack of denaturation. Consequently, they appear localized near the top of the gel after the electrophoresis run. The visibility of these proteins can still be achieved after staining, provided they have denatured and bound to SDS.