TY - JOUR
T1 - Kinetic parameters and recognition of thymidine analogues with varying functional groups by thymidine phosphorylase
AU - Hatano, Akihiko
AU - Harano, Aiko
AU - Takigawa, Yoshikatsu
AU - Naramoto, Yasuhiro
AU - Toda, Keisuke
AU - Nakagomi, Yuuichi
AU - Yamada, Hideyuki
N1 - Funding Information:
This research was supported partly by the Astellas Foundation for Research on Medicinal Resources and Hamamatsu Science and Technology Foundation.
PY - 2008/4/1
Y1 - 2008/4/1
N2 - Thymidine phosphorylase (TP, EC 2.4.2.4) recognized the structure of the substrate with high specificity, via both the base and the ribosyl moieties. The replacement of 3′-OH of thymidine markedly influenced its catalytic activity with TP. The conversion of pyrimidine nucleosides with modified base moieties to the corresponding 1-phosphate form was poor. The leaving group activity decreased with an increase in aromaticity of the pyrimidine base moiety, because of increased difficulty in polarizing the base by the amino acids local to the active site. The replacement of 3′ and 5′ functional groups tended to decrease the reaction rate and the percentage conversion with TP. In particular the ribosyl 3′ hydroxyl group was structurally important for the binding of the substrate by the enzyme. The kinetic assay clearly showed high Km and low Vmax values on replacing the 3′ hydroxyl group with hydrogen.
AB - Thymidine phosphorylase (TP, EC 2.4.2.4) recognized the structure of the substrate with high specificity, via both the base and the ribosyl moieties. The replacement of 3′-OH of thymidine markedly influenced its catalytic activity with TP. The conversion of pyrimidine nucleosides with modified base moieties to the corresponding 1-phosphate form was poor. The leaving group activity decreased with an increase in aromaticity of the pyrimidine base moiety, because of increased difficulty in polarizing the base by the amino acids local to the active site. The replacement of 3′ and 5′ functional groups tended to decrease the reaction rate and the percentage conversion with TP. In particular the ribosyl 3′ hydroxyl group was structurally important for the binding of the substrate by the enzyme. The kinetic assay clearly showed high Km and low Vmax values on replacing the 3′ hydroxyl group with hydrogen.
KW - Kinetic parameters
KW - Substrate recognition
KW - Thymidine analogues
KW - Thymidine phosphorylase
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U2 - 10.1016/j.bmc.2008.01.038
DO - 10.1016/j.bmc.2008.01.038
M3 - Article
C2 - 18272369
AN - SCOPUS:41649102610
VL - 16
SP - 3866
EP - 3870
JO - Bioorganic and Medicinal Chemistry
JF - Bioorganic and Medicinal Chemistry
SN - 0968-0896
IS - 7
ER -