Error in SDS PAGE - (Feb/21/2005 )

the reported wight of my protein is 66 KD with two subunit of sixe 46 and 20 KD. but a sinlge band at around 60 KD is visible in my 12%SDS PAGE.

If your loading dye does not contain enough DTT with SDS, then the sample may not be fully denatured.If you have an activity assay, test it and see if the addition of reducing agent kills the activity. You may have some sidulfide bonds between the subunits. Try running a gradient gel from 10-20% or so. It has much better resolution around 40 than the 12%. Also you can have MS/MS done that can identify the proteins no problem to show that they are the right protein.