From Big Medical Encyclopedia

THYMIDINE (1 - beta D-2-dezoksiribofuranozil thymine, 5-metildezoksi-uridine, 2-dezoksiribonukleozid thymine) — biologically active agent, one of the major intermediate compounds in biosynthesis of nucleic acids and coenzymes, it is eurysynusic in wildlife, is present at all animals and vegetable fabrics.

Fiziol. role of T. di - and trifosforilirovanny derivative (nucleotides), formed in the course biol is connected with the fact that it 5 '-mono-. phosphorylations (see), are predecessors of nucleic acids (see) and are directly involved in their synthesis and metabolism. For functioning nucleinic to - crucial importance specific not covalent interactions between certain couples of the reasons in on-linukleotidnoy a chain have t. So-called complementary couples resulting from such interactions are stabilized due to formation of hydrogen bindings. Thymine (T) of thymidine with other heterocyclic base — the adenine (A) which is a part of a nucleoside of adenosine is capable to form complementary couple And —

T. T. represents beta N - pentafuranozid heterocyclic nitrogen base of thymine (see. Pirimidinovy bases ). In a molecule T. the first carbon atom of a 2-dezoksi-D-ribose is connected by a N-glycosidic linkage with the first nitrogen atom of thymine, at the same time the 2-dezoksp-D-ribose is in a furanozny form (see. Desoxyribose ).

T. let's well dissolve in water, it is rather steady against effect of alkalis and diluted to - t and only after the long processing concentrated to - that is split on thymine and desoxyribose. T. possesses absorption, characteristic of nucleosides, in the UF-part of a range, it is identified by means of methods of thin layer chromatography (see) and paper chromatographies, and also the corresponding staining reactions on carbohydrates (see) on the maintenance of a carbohydrate component.

In an organism of T. it is formed of thymine during synthesis thymidine-5' - monophosphate with the participation of enzymes of thymidinephosphorylase (KF and a thymidinekinase (KF As T. in a cell under the influence of the corresponding kinases quickly turns into thymidine-5 '-triphosphate, one of important experimental receptions for studying of metabolism nucleinic to - the t in biochemistry and medicine is administration of radioactive thymidine (usually 3H-thymidine) in composition of in vivo DNA.

Receive T. by enzymic hydrolysis of deoxyribonucleic acid (see) specific DNA-ase with the subsequent splitting of the formed oligonucleotides phosphoesterases and nukleozidfosfataza; besides, T. it is possible to receive in the synthetic way.

Bibliography: Davidson D. Biochemistry of nucleic acids, the lane with English, M., 1976; Mickelson A. Chemistry of nucleosides and nucleotides, the lane with English, M., 1966; Shabarova 3. And. and Bogdanov of A. A. Himiya of nucleic acids and their components, M., 1978.

P. L. Ivanov.