Deoxythymidine is the more common name of 1-(2-deoxy-β-D-ribofuranosyl)-5-methyluracil. The name thymidine is also in common use. Deoxythymidine is an important component of DNA (deoxyribonucleic acid).
What is deoxythymidine?
Deoxythymidine is a nucleoside with the molecular formula C10H14N2O5. A nucleoside is a molecule consisting of what is called a nucleobase and a monosaccharide, pentose. Deoxythymidine was one of the first building blocks of DNA to be discovered. This is why DNA was initially also called thymidyl acid. Only much later was it renamed deoxyribonucleic acid. However, thymidine is not only a nucleoside of DNA, but also a nucleoside of tRNA. The tRNA is the transfer RNA. Chemically, deoxythymidine consists of the base thymine and the monosaccharide deoxyribose. Both ring systems are connected by an N-glycosidic bond. Thus, the base can rotate freely in the molecule. Like all pyrimidine nucleosides, deoxythymidine is acid stable.
Function, action, and roles
Deoxythymidine is a nucleoside formed from thymine and deoxyribose. Thus, it is a compound of a nucleic base (thymine) and a pentose (deoxyribose). This compound forms the basic building block of nucleic acids. A nucleic acid is a so-called heteropolymer. It consists of several nucleotides linked together by phosphate esters. Through the chemical process of phosphorylation, nucleosides are built up into nucleotides. During phosphorylation, groups of phosphates or pyrophosphates are transferred to a target molecule, in this case to the nucleotides. The nucleoside deoxythymidine belongs to the organic base (nucleic base) thymine. In this form, deoxythymidine functions as the basic building block of DNA. DNA is a large molecule that is very rich in phosphorus and nitrogen. It functions as a carrier of genetic information. DNA is made up of two single strands. These run in opposite directions. The shape of these strands is reminiscent of a rope ladder, which means that the individual strands are connected by a kind of spar. These spars are formed from two of the organic bases in each case. Besides thymine, there are also the bases adenine, cytosine and guanine. Thymine always forms a bond with adenine. Two hydrogen bonds form between the two bases. DNA is located in the nuclei of somatic cells. The task of DNA, and thus also the task of deoxythymidine, is to store hereditary information. It also encodes protein biosynthesis and thus, to a certain extent, the “blueprint” of the respective living organism. All processes in the body are influenced by this. Disturbances within the DNA therefore also lead to serious disturbances within the body.
Formation, occurrence, properties and optimal values
Basically, deoxythymidine consists only of carbon, hydrogen, nitrogen and oxygen. The body would also be able to synthesize nucleosides itself. However, synthesis is quite complex and very time-consuming, so only a portion of deoxythymidine is produced this way. In order to save energy, the body engages in a kind of recycling here and uses the so-called salvage pathway. Purines are formed during the breakdown of nucleic acids. Through various chemical processes, nucleotides and thus nucleosides can be recovered from these purine bases.
Diseases and disorders
DNA damage can occur as a result of deoxythymidine impairment. Possible causes of DNA damage include defective metabolic processes, chemical substances, or ionizing radiation. Ionizing radiation includes, for example, UV radiation. One disease in which DNA plays an important role is cancer. Every day, tens of millions of cells multiply in the human body. It is important for smooth reproduction that the DNA is undamaged, complete and free of errors. Only then can all the relevant genetic information be passed on to the daughter cells. Factors such as UV radiation, chemicals, free radicals or high-energy radiation can not only damage the cell tissue, but also lead to errors in the duplication of DNA during cell division. As a result, the genetic information contains faulty information. Normally, cells have a repair mechanism. This means that minor damage to the genetic material can actually be repaired. However, it can happen that the damage is passed on to the daughter cells. This is also referred to as mutations of the genetic material.If too many mutations are found in the DNA, healthy cells usually initiate programmed cell death (apoptosis) and destroy themselves. This is to prevent the damage to the genetic material from spreading further. Cell death is initiated by various signaling devices. Damage to these signal transducers appears to play an important role in cancer development. If they do not respond, the cells do not destroy themselves and the damage to the DNA is passed on from cell generation to cell generation. Thymine, and thus deoxythymidine, appears to be particularly significant in the processing of UV radiation. UV radiation can lead to mutations of DNA, as already mentioned. CPD damage is particularly common as a result of UV radiation. In these CPD damages, two thymine building blocks usually combine to form a so-called dimer and form a solid unit. As a result, the DNA can no longer be read correctly and the cell dies or, in the worst case, skin cancer develops. This process is completed just one picosecond after absorption of the UV rays. For this to happen, however, the thymine bases must be present in a specific arrangement. Since this is not so often the case, the damage caused by UV radiation is still limited. However, if the genome is distorted so that more thymins are in the correct arrangement, there is also increased formation of dimers and thus greater damage within the DNA.
