My understanding is that it was introduced for cases where an error in the sequence was discovered long after a large body of literature had accumulated for the "wrong" sequence. That is, imagine some enzyme where an important catalytic active site residue was number "152", and lots of people had been talking about this residue for years. Then, when you solve the 3D structure, you discover that there is actually a glycine between residues "32" and "33", what do you do? Do you change 152 to 153 and put up with all the angry letters from enzymologists, telling you that you mislabeled this important residue? In case you don't want to do this, the PDB allows you to put in a residue "32A". Deletions can happen too, but they are easier to deal with from a file format standpoint.
-James Holton MAD Scientist On 5/3/2011 6:27 AM, Jahan Alikhajeh wrote:
Dear Friends, I have noticed an issue in a pdb file, the term "insertion code". Does anyone know anything about it? what is it used for? Thanks in Advance, Jahan Alikhajeh, Ph.D, Technical Supervisor, MAN Corporation LTD, Keshavarz Boulevard, Ghods Avenue No. 41, 5th Floor, Tehran, Iran, 14177, Tel: +982166282841 Fax: +982166282997
