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Substrate Specificity of Escherichia coli Thymidine Phosphorylase


N. G. Panova1*, 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
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 (Km, KI, kcat) 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.
KEY WORDS: thymidine phosphorylase, thymidine derivatives, substrate specificity, inhibitors, analysis in terms of steric interactions

DOI: 10.1134/S0006297907010026