EC Number   |
|---|
   2.1.1.297 | analysis of the crystal structure of the HemK N-terminal domain, PDB ID 1T43 |
| 2.1.1.297 | crystallized in the presence of S-adenosylmethionine at 223°C using ammonium sulfate as the precipitant. X-ray diffraction data are collected to 2.5 A resolution from a native crystal. The crystal is orthorhombic, belonging to the space group I222 (or I2(1)2(1)2(1)), with unit-cell parameters of a = 104.24, b = 118.73, and c = 146.62 A. Two (or three) monomers of recombinant HemK are likely to be present in the crystallographic asymmetric unit |
| 2.1.1.297 | molecular replacement based on the data of Thermotoga maritima enzyme, in complex with the methyl-donor product S-adenosyl-L-homocysteine. Enzyme HemK contains two domains: a putative substrate binding domain at the N-terminus consisting of a five helix bundle and a seven-stranded catalytic domain at the C-terminus that harbors the binding site for S-adenosyl-L-homocysteine. The two domains are linked by a beta-hairpin. The apparent hinge mobility of the two domains may reflect functional importance during the reaction cycle |
| 2.1.1.297 | to 2.2 A resolution. The C-terminal domain of PrmC adopts the canonical S-adenosyl-L-methionine-dependent methyltransferase fold and shares structural similarity with the nucleotide N-methyltransferases in the active site, including use of a conserved (D/N)PPY motif to select and position the glutamine substrate. Residues of the PrmC 197NPPY200 motif form hydrogen bonds that position the planar Gln side chain such that the lone-pair electrons on the nitrogen nucleophile are oriented toward the methyl group of S-adenosyl-Lmethionine. In the product complex, the methyl group remains pointing toward the sulfur, consistent with either an sp3-hybridized, positively charged Gln nitrogen, or a neutral sp2-hybridized nitrogen in a strained conformation. Due to steric overlap within the active site, proton loss and formation of the neutral planar methylamide product are likely to occur during or after product release |
