I am running my first gradient sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE) protein gel (4-20%). It is well known that there is an approximately linear correlation between the logarithm of molecular weight and relative mobility of a protein. Does anyone happen to know if the same holds true for gradient gels. I think it should, and we will find out later. BTW some polypeptides are known to behave anomalously with respect to their mobility. This might be the result of how much dodecyl sulfate that they bind.