RELIABILITY OF MOLECULAR-WEIGHT DETERMINATION OF PROTEINS BY POLYACRYLAMIDE GRADIENT GEL-ELECTROPHORESIS IN PRESENCE OF SODIUM DODECYL-SULFATE

Thirty-four proteins with molecular weights (MWs) between 1.3 × 104 and 9.5 × 105 and seven polypeptide chains of some of these proteins were incubated in sodium dodecyl sulfate and submitted to electrophoresis in a polyacrylamide gradient gel (3 to 30%; relative percentage of bisacrylamide: 8.4%). Analysis of the results confirmed the reliability of the relationship: log(MW) = alog(T) + b, where T is the polyacrylamide concentration reached by a protein, a is the slope, and b is the Y intercept of the regression line. In fact the mean deviation between the expected and the observed MW was ±5.5%. In addition we have shown that MWs of unreduced and reduced proteins can be estimated with the same accuracy and tha MWs of glycoproteins can also be determined with the same accuracy as other proteins. © 1978.