1a16: Difference between revisions

The structure of the proline-specific aminopeptidase (EC 3.4.11.9) from, Escherichia coli has been solved and refined for crystals of the native, enzyme at a 2.0-A resolution, for a dipeptide-inhibited complex at 2.3-A, resolution, and for a low-pH inactive form at 2.7-A resolution. The, protein crystallizes as a tetramer, more correctly a dimer of dimers, at, both high and low pH, consistent with observations from analytical, ultracentrifuge studies that show that the protein is a tetramer under, physiological conditions. The monomer folds into two domains. The active, site, in the larger C-terminal domain, contains a dinuclear manganese, center in which a bridging water molecule or hydroxide ion appears poised, to act as the nucleophile in the attack on the scissile peptide bond of, Xaa-Pro. The metal-binding residues are located in a single subunit, but, the residues surrounding the active site are contributed by three, subunits. The fold of the protein resembles that of creatine, amidinohydrolase (creatinase, not a metalloenzyme). The C-terminal, catalytic domain is also similar to the single-domain enzyme methionine, aminopeptidase that has a dinuclear cobalt center.

1A16 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with MN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Xaa-Pro_aminopeptidase Xaa-Pro aminopeptidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.11.9 3.4.11.9] Structure known Active Site: NUL. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1A16 OCA].  

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