Denaturing polyacrilamide gel-electrophoresis (SDS-PAGE) is the best known method in biochemistry is used to separate proteins according to their size. Proteins on this gel: BSA (66.2 kDa), ovalbumin (45 kDa), TEV-protease (31 kDa), luciferases MLuc39 (23 kDa), MLuc7 (17 kDa) and lysozyme (14.4 kDa).