A protein gives a single band on sds gel electrophoresis, as shown in lanes 1 and 2 below. there is little if any effect from adding β-mercaptoethanol (bme) to the sample; if anything, the protein runs a little bit slower. when treated with the proteolytic enzyme thrombin and electrophoresis in the absence of bme, the protein migrates a bit more rapidly (lane 3). but if bme is present, two much more rapidly migrating bands are found (lane 4).
