Dear all, I solved a protein crystal structure which is about 95KD and was purified from pig liver. Based on the crystal structure, I missed 36 residues at its N-terminus and 16 at its C-terminus. I tried to do N-terminus sequencing to identify if these 36 residues was cleaved or not. However, the N-terminus sequencing failed. One of the possibilities is that the N-terminus has been blocked by some post-translational modifications, such as acetylation and methylation, which leave no free NH2 group. Can anybody give me some suggestions about how I can deblock the modifications so that I can do N-terminus sequencing? Or any other suggestions on how to identify from which residue my protein starts (Other techniques).
Thanks you very much in advance. Best wishes Wei Yong
