Substrate Specificity of Escherichia coli Thymidine Phosphorylase

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N. G. Panova^1*, C. S. Alexeev¹, A. S. Kuzmichov¹, E. V. Shcheveleva¹, S. A. Gavryushov¹, K. M. Polyakov¹, A. M. Kritzyn¹, S. N. Mikhailov¹, R. S. Esipov², and A. I. Miroshnikov²

¹Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, ul. Vavilova 32, 119991 Moscow, Russia; fax: (495) 135-1405; E-mail: natasha@eimb.ru; smikh@eimb.ru

²Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, 117997 Moscow, Russia; fax: (495) 330-7410

^* To whom correspondence should be addressed.

Received April 4, 2006; Revision received August 16, 2006

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Substrate specificity of Escherichia coli thymidine phosphorylase to thymidine derivatives modified at 5´-, 3´-, and 2´,3´- positions of the sugar moiety was studied. Equilibrium and kinetic constants (K_m, K_I, k_cat) of the phosphorolysis reaction have been determined for 20 thymidine analogs. The results are compared with X-ray and molecular dynamics data. The most important hydrogen bonds in the enzyme-substrate complex are revealed.

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KEY WORDS: thymidine phosphorylase, thymidine derivatives, substrate specificity, inhibitors, analysis in terms of steric interactions

DOI: 10.1134/S0006297907010026

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