I know it forms a dimer but the dimer does not run at the doubled molecular weight.
Dear Patrick
just some question?
which gel are you using? which acrilamide %? how do you prepare the sample before loading?
You need to consider that SDS-gel is a denaturing gel therefore for soluble proteins in the most of cases, expecially if you add reducing agent and boil the sample prior to load in gel you will see only the monomeric form of your protein. Sometimes if the dimerization is mediated by S-S bond you can see the dimer with.out addition of DTT to the loading buffer or just in rare cases if the dimer is really stable you can see it if you do not boild the sample but it is strictly depends form the properties of your specific proteins.
So probably you will not see the dimer in SDS-page. To see it you need to perform a native page as blue native or perform a SEC chromatography.
Dear Patrick
just some question?
which gel are you using? which acrilamide %? how do you prepare the sample before loading?
You need to consider that SDS-gel is a denaturing gel therefore for soluble proteins in the most of cases, expecially if you add reducing agent and boil the sample prior to load in gel you will see only the monomeric form of your protein. Sometimes if the dimerization is mediated by S-S bond you can see the dimer with.out addition of DTT to the loading buffer or just in rare cases if the dimer is really stable you can see it if you do not boild the sample but it is strictly depends form the properties of your specific proteins.
So probably you will not see the dimer in SDS-page. To see it you need to perform a native page as blue native or perform a SEC chromatography.
Dear Patrik,
From your question I understand that your protein is dimeric but when you run SDS PAGE you get a band of 86 KD and you are not getting doubled the molecular weight. This simply means that your protein is a homodimer with identical molecular weights and so when you will run an SDS PAGE under reducing conditions, all the S-S bonds will be broken and both the dimers would overlap being identical thereby giving you an intense band at 86 KD. If you wish to prove the your protein is dimer, you need to run SDS PAGE under non-reducing conditions wherein your S-S bonds will remain intact and you will get an band around~170 KD. I hope I have been able to answer your question... Wish you good luck...Best regards
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