Should I consider adding a Cysteine in peptides for making antibodies?
Chemical conjugation using Cysteine offers a single point attachment provided there is just one Cys in the sequence (added or part of the native sequence). It is preferable to add Cys at the NH2 terminus if the peptide is internal or it represents the very C-terminus. This will keep the COOH free (non-conjugated) as it exists in native protein. For peptides representing the very NH2-terminal sequences, Cys should be added at the C-terminus of the peptide. For internal peptides, Cys can be added at either end but it is easier to synthesize peptides containing a NH2-terminal Cysteine. Cysteine can also be used to couple peptides to Sepharose for affinity purification of antibodies. Amino or COOH-conjugation chemistries should be avoided as most peptides contain several NH2 and COOH groups available in a given peptide sequence resulting into multi-point attachment and peptide distortion.
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05/08/2013