Once your samples have been diluted with loading buffer, it’s time to heat things up. Use a heat block or boiling water, heat samples to 95-100°C. The amount of time required for heat varies between protocols, but it is generally 2-10 minutes.
Heat ensures that your samples are truly denatured. In addition, heat loosens up samples gummy from DNA and cellular debris, making the samples easier to load.
So that’s the long answer as to why you heat protein samples prior to loading. The short answer? Because that’s the way you do it!
If you have any questions, send them along. We will do our best to answer them.