Molecular dynamics simulation of a human thiopurine S-methyltransferase complexed with 6-mercaptopurine model |
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Authors: | Wanwimon Mokmak Sissades Tongsima Ekachai Jenwitheesuk |
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Institution: | 1.National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, 113 Thailand Science Park, Phahonyothin Road, Klong 1, Klongluang, Pathumthani 12120, Thailand |
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Abstract: | Human thiopurine S-methyltransferase (TPMT) is an essential protein in 6-mercaptopurine (6MP) drug metabolism. To understand the
pharmacogenetics of TPMT and 6MP, X-ray co-crystal structures of TPMT complexes with S-adenosyl-L-methionine (AdoMet) and 6MP
are required. However, the co-crystal structure of this complex has not been reported because 6MP is poorly water soluble. We used
molecular dynamics (MD) simulation to predict the structure of the complex of human TPMT-AdoHcy(CH2)6MP, where the sulfur atoms of
AdoHcy and 6MP were linked by a CH2 group. After 1300 picoseconds of MD simulation, the trajectory showed that 6MP was stabilized in
the TPMT active site by formation of non-bonded interactions between 6MP and Phe40, Pro196 and Arg226 side chains of TPMT. The
intersulfur distance between AdoHcy and 6MP as well as the binding modes and the interactions of our TPMT-AdoHcy model are
consistent with those observed in the X-ray crystal structure of murine TPMT-AdoHcy-6MP complex. The predicted binding modes of
AdoHcy and 6MP in our model are consistent with those observed in murine TPMT X-ray crystal structures, which provides structural
insights into the interactions of TPMT, AdoHcy, and 6MP at the atomic level and may be used as a starting point for further study of
thiopurine drug pharmacogenetics. |
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Keywords: | methyltransferase ligand molecular dynamics simulation structural changes |
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