DNA and Thymine
Generally, all complex substances are made up of smaller building blocks, considering an example where our house is built with bricks, stones, woods, etc. and as the same; our body is made up of cells which form the basic unit of live.
Likewise, DNA is also made up of smaller molecules which together functions as the important substance to live in.
We know that DNA is a complex molecule made up many substances like phosphoric acid, sugar (5-carbon) and nucleobases.
There are five nitrogenous bases which serves as the most vital and important component in the functioning of the DNA.
The nuclear bases are mostly of adenine, guanine, thymine and cytosine, and uracil in case of RNA. These bases are generally classified into two types namely purine and pyrimidine.
What is Thymine?
Thymine is one of the four bases which is needed for the DNA, to make it as one of the structural and functional unit. Whereas the other three bases such as adenine, guanine, and cytosine also play an important role.
Thymine is located in one strand and always pairs up with adenine which is present on its opposite strand.
These bases in a sequentially manner greatly helps in instructing and transferring the genetic information for the present generations and it is later carrying out to future generations.
Thymine is abbreviated and it is referred to as the nucleotide T.
It is also chemically known as 5-methyluracil. It was first isolated by Albrecht Kossel and Albert Neumann from the thymus gland in the year 1893.
Structure of Thymine
A ring-shaped pyrimidine molecule is generally considered as the chemical structure of thymine. Which is equally shared among each of the molecules.
At the time of formation of DNA, thymine always combines with thymine with the help of two hydrogen bonds.
These hydrogen bonds create a stabilizing nature for the structure of nucleic acid.
Following the same way guanine and cytosine pairs up with each other. While moving forward to each generation.
However, when these molecules are exposed to ultra violet and some other heavier radiation it causes mutations in the DNA which leads to several disorders. Where thymine dimer also occurs during this condition.
But thymine is not present in RNA, whereas there it is replaced by Uracil.
The chemical name of thymine is 5-methyluracil. Which implies that it has been derived from methylation of uracil in the 5th position of carbon, in that case methyl (-CH3) is added to the ring of pyrimidine so that the thymine is scientifically referred to as 5-Methyluracil.
Features of Thymine
Thymine usually has a pyrimidine nucleobase with a chemical formula C5H6N2O2. It belongs to the group of pyrimidine which is a heterocyclic aromatic organic compound having a single ring, which combines with an alternating carbon and nitrogen atoms.
This ring is generally known as pyrimidine rings. It has its molar mass of 126.115 gram per mol and it has a melting point of 316 to 317ºC. It usually occurs as one of the compounds in nucleoside which is made up of nucleobase and a sugar component namely deoxyribose or ribose.
It may occur in nucleotide. Thymine is considered as of the primary nucleobases out of five nucleobases that are found in the nucleic acids. Where thymine and uracil are considered as complementary pairs with Adenine.
On combining thymine with deoxyribose, it results in the formation of nucleoside deoxythymidine and is commonly referred to as thymidine.
This thymidine often undergoes phosphorylation when phosphoryl acid groups are added to it, it forms monophosphate thymidine, diphosphate thymidine, triphosphate thymidine accordingly. With the number of phosphoric acid groups added to it.
Thymine Mutation and Cancer
When the chemical nature of thymine gets mutated it becomes defective in such cases the DNA becomes mutated and it leads to the formation of melanoma.
A common cause for mutation that occurs due to the defect in thymine is mostly due to ultra violet radiations because these light waves cause the thymine bases to form a dimer which are located on its adjunct sides.
This changes the nature of the structure of the DNA and it results in the formation of mutation by affecting the functions of DNA.
This alteration in the function of DNA may cause deregulation in the cell division and its functioning which has a high risk of developing cancers and other tumors.
The usual treatment for cancer is done by introducing fluorouracil which on incorporating into the DNA can inhibit the function of cancer cells and it also helps in the formation of healthy new DNA in the newly formed cells.
Biological Reactions of Thymine
Thymine is almost similar to that of other bases which are present in the DNA. It is formed in several steps. First step in the formation of thymine involves a formation of carbamoyl phosphate from a reaction of bicarbonate, glutamine, ATP and water molecule.
This process is being catalyzed by the enzyme carbamoyl phosphate synthetase. Which helps in converting carbamoyl phosphate into carbonyl aspartate by again undergoing a catalytic activity with the enzyme aspartate transcarboxylase which is further converted into 5-phospho-α-D-ribosy-1-phosphorylate.
Whereas this phosphate orates to form an oratidine 5- monophosphate. Which is further decarboxylated by the enzyme OMP decarboxylase and helps in yielding uridine monophosphate (UMP).
At the same time Uridine diphosphate and uridine triphosphate are synthesized by the biosynthetic process with the help of kinase along with the dephosphorylation of ATP molecules.
To produce thymine, uridine is reduced to deoxy uridine with the help of an enzyme ribonucleic reductase which is further methylated by the enzyme thymidyl synthetase to produce thymine.
Function of Thymine
Thymine is considered as one of the important base pair in the primary nucleobases among five base pairs. This is considered as one of the base pair which helps in forming the fundamental genetic code of DNA.
Where as the nucleic acids like DNA and RNA which have their own genetic functions, which helps in coding the particular sequence of proteins that are very much important for the functioning of the body.
Where as these nucleic acids like thymine plays a great role in maintaining the hereditary of the organism which helps in function of the cell and its metabolic activities.