Yoon Hye-Jin, Kang Kyung Yi, Ahn Hyung Jun, Shim Sun Mi, Ha Jun-Yong, Lee Soo-Kyoung, Mikami Bunzo, Suh Se Won
Structural Proteomics Laboratory, School of Chemistry and Molecular Engineering, Seoul National University, Seoul 151-742, Korea.
Mol Cells. 2003 Oct 31;16(2):266-9.
The enzyme HemK (or PrmC) is one of the first identified methyltransferases that modify glutamine. It methylates the highly conserved GGQ motif in class I release factors (RF1 and RF2) in Escherichia coli. HemK from Thermotoga maritima was over-expressed and crystallized in the presence of S-adenosylmethionine at 296 K using ammonium sulfate as the precipitant. X-ray diffraction data were 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, giving a V(M) of 3.62 A3 Da(-1) (or 2.41 A3 Da(-1)), with a solvent content of 62.7% (or 44.0%).
HemK酶（或PrmC）是最早被鉴定出的修饰谷氨酰胺的甲基转移酶之一。它能使大肠杆菌中I类释放因子（RF1和RF2）里高度保守的GGQ基序发生甲基化。嗜热栖热菌的HemK在296 K下，以硫酸铵作为沉淀剂，在S-腺苷甲硫氨酸存在的情况下进行了过量表达和结晶。从天然晶体收集到了分辨率为2.5 Å的X射线衍射数据。该晶体为正交晶系，属于空间群I222（或I2(1)2(1)2(1)），晶胞参数为a = 104.24、b = 118.73和c = 146.62 Å。重组HemK的两个（或三个）单体可能存在于晶体学不对称单元中，V(M)为3.62 Å3 Da-1（或2.41 Å3 Da-1），溶剂含量为62.7%（或44.0%）。
