Hi there,

What you are actually looking for is a protein quantification method, isn't it? I don't think  trying to quantify Nter and Cter is a good idea as these chemical groups also exist in some side-chains and therefore will affect the quantification...

Hi Liger,

Thank you for your response.

Can you please tell me that an enzyme/antibody/proteins have equal number of C and N terminals or different Number? If so..

what is the standard method to prove this?

Thanks in advance.

Have a great time.

Hi again,

A protein can be formed from the assembly of polypeptide chains so proteins containing different numbers of polypeptides will contain different number of Nter/Cter.  Quantification of Cter and Nter isn't easy as there are some carboxylic and amine functions in amino acid side chain which will cross react with the reagent you intend to target to the N or Cter. What you are looking for is the determination of oligomerization state of a given protein (its content in terms of number of and nature of polypeptide chains). To do so, you have first to purify the protein of interest and then determineit's native MW by SEC and identify its chain content by SDS/PAGE. And run MS on SDS/PAGE bands in order to identify their content ...