1psc
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PHOSPHOTRIESTERASE FROM PSEUDOMONAS DIMINUTA
OverviewOverview
Phosphotriesterase, as isolated from Pseudomonas diminuta, is capable of, detoxifying widely used pesticides such as paraoxon and parathion and, various mammalian acetylcholinesterase inhibitors. The enzyme requires a, binuclear metal center for activity. Recently, the three-dimensional, structure of the apoenzyme was solved (Benning et al., 1994) and shown to, consist of an alpha/beta-barrel. Here we describe the three-dimensional, structure of the holoenzyme, reconstituted with cadmium, as determined by, X-ray crystallographic analysis to 2.0-A resolution. Crystals employed in, the investigation belonged to the space group C2 with unit cell dimensions, of a = 129.5 A, b = 91.4 A, c = 69.4 A, beta = 91.9 degrees, and two, subunits in the asymmetric unit. There are significant differences in the, three-dimensional architecture of the apo and holo forms of the enzyme, such that their alpha-carbon positions superimpose with a root-mean-square, deviation of 3.4 A. The binuclear metal center is located at the, C-terminus of the beta-barrel with the cadmiums separated by 3.8 A. There, are two bridging ligands to the metals: a water molecule (or possibly a, hydroxide ion) and a carbamylated lysine residue (Lys 169). The more, buried cadmium is surrounded by His 55, His 57, Lys 169, Asp 301, and the, bridging water in a trigonal bipyramidal arrangement. The second metal is, coordinated in a distorted octahedral geometry by His 201, His 230, Lys, 169, the bridging water molecule, and two additional solvents.
About this StructureAbout this Structure
1PSC is a Single protein structure of sequence from Brevundimonas diminuta with CD, EBP and FMT as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Three-dimensional structure of the binuclear metal center of phosphotriesterase., Benning MM, Kuo JM, Raushel FM, Holden HM, Biochemistry. 1995 Jun 27;34(25):7973-8. PMID:7794910
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