1xrb
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S-ADENOSYLMETHIONINE SYNTHETASE (MAT, ATP: L-METHIONINE S-ADENOSYLTRANSFERASE, E.C.2.5.1.6) IN WHICH MET RESIDUES ARE REPLACED WITH SELENOMETHIONINE RESIDUES (MSE)
OverviewOverview
The structure of S-adenosylmethionine synthetase (MAT, ATP:L-methionine S-adenosyltransferase, EC 2.5.1.6.) from Escherichia coli has been determined at 3.0 A resolution by multiple isomorphous replacement using a uranium derivative and the selenomethionine form of the enzyme (SeMAT). The SeMAT data (9 selenomethionine residues out of 383 amino acid residues) have been found to have a sufficient phasing power to determine the structure of the 42,000 molecular weight protein by combining them with the other heavy atom derivative data (multiple isomorphous replacement). The enzyme consists of four identical subunits; two subunits form a spherical tight dimer, and pairs of these dimers form a peanut-shaped tetrameric enzyme. Each pair dimer has two active sites which are located between the subunits. Each subunit consists of three domains that are related to each other by pseudo-3-fold symmetry. The essential divalent (Mg2+/Co2+) and monovalent (K+) metal ions and one of the product, Pi ions, were found in the active site from three separate structures.
About this StructureAbout this Structure
1XRB is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as Methionine adenosyltransferase, with EC number 2.5.1.6 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structure of S-adenosylmethionine synthetase., Takusagawa F, Kamitori S, Misaki S, Markham GD, J Biol Chem. 1996 Jan 5;271(1):136-47. PMID:8550549
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