| Primary Identifier | IPR023213 | Type | Homologous_superfamily |
| Short Name | CAT-like_dom_sf |
| description | Chloramphenicol acetyltransferase (CAT) catalyses the acetyl-CoA dependent acetylation of chloramphenicol, resulting in the inactivation of the antibiotic. The crystal structure of the type III enzyme from Escherichia coli with chloramphenicol bound has been determined. CAT is a trimer of identical subunits (monomer Mr 25,000) and the trimeric structure is stabilised by a number of hydrogen bonds, some of which result in the extension of a β-sheet across the subunit interface. Chloramphenicol binds in a deep pocket located at the boundary between adjacent subunits of the trimer, such that the majority of residues forming the binding pocket belong to one subunit while the catalytically essential histidine belongs to the adjacent subunit. His195 is appropriately positioned to act as a general base catalyst in the reaction, and the required tautomeric stabilisation is provided by an unusual interaction with a main-chain carbonyl oxygen [].This superfamily represents a domain characteristic of trimeric enzymes with the active sites being located in between subunits, including chloramphenicol acetyltransferase. |
