Wu Hong, Horton John R, Battaile Kevin, Allali-Hassani Abdellah, Martin Fernando, Zeng Hong, Loppnau Peter, Vedadi Masoud, Bochkarev Alexey, Plotnikov Alexander N, Cheng Xiaodong
Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada.
Proteins. 2007 Apr 1;67(1):198-208. doi: 10.1002/prot.21272.
Human thiopurine S-methyltransferase (TPMT) exhibits considerable person-to-person variation in activity to thiopurine drugs. We have produced an N-terminal truncation of human TPMT protein, crystallized the protein in complex with the methyl donor product S-adenosyl-L-homocysteine, and determined the atomic structure to the resolution of 1.58 and 1.89 A, respectively, for the seleno-methionine incorporated and wild type proteins. The structure of TPMT indicates that the naturally occurring amino acid polymorphisms scatter throughout the structure, and that the amino acids whose alteration have the most influence on function are those that form intra-molecular stabilizing interactions (mainly van der Waals contacts). Furthermore, we have produced four TPMT mutant proteins containing variant alleles of TPMT*2, *3A, *3B, and *3C and examined the structure-function relationship of the mutant proteins based on their expression and solubility in bacteria and their thermostability profile.
人硫嘌呤S-甲基转移酶（TPMT）对硫嘌呤类药物的活性在个体之间存在显著差异。我们制备了人TPMT蛋白的N端截短体，使其与甲基供体产物S-腺苷-L-高半胱氨酸形成复合物并结晶，分别测定了掺入硒代甲硫氨酸的蛋白和野生型蛋白的原子结构，分辨率分别为1.58 Å和1.89 Å。TPMT的结构表明，天然存在的氨基酸多态性分散在整个结构中，而那些改变对功能影响最大的氨基酸是形成分子内稳定相互作用（主要是范德华接触）的氨基酸。此外，我们制备了四种含有TPMT *2、*3A、3B和3C变异等位基因的TPMT突变蛋白，并根据它们在细菌中的表达、溶解性及其热稳定性概况研究了突变蛋白的结构-功能关系。
