[BiO BB] The 'X' amino acids in DSSP

Iddo Friedberg idoerg at cc.huji.ac.il
Tue Apr 16 04:07:12 EDT 2002

On Tue, 16 Apr 2002, Qiang Lu wrote:

: Hi friends,
: In DSSP database, there are 'X' amino acids, other than A C D E ...
: (i.e. 20 amino acids). Do you know what does it mean?

An amino-acid which is not one of the 20. Usually a covalent modification
produced by protein engineering, but I've also seen phosphorylated
residues marked as `X'. Another option is may be the 21st amino-acid,
Selenocysteine. I suggest you check the particular `X' you are interested
in by looking at the original PDB file from which the DSSP file was




Iddo Friedberg                                  | Tel: +972-2-6757374
Dept. of Molecular Genetics and Biotechnology   | Fax: +972-2-6757308
The Hebrew University - Hadassah Medical School | email: idoerg at cc.huji.ac.il
POB 12272, Jerusalem 91120                      |
Israel                                          |

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