In genetics, A stands for adenine, one member of the A-T (adenine-thymine) base pair in DNA. The other base pair in DNA is G-C (guanine-cytosine).
Each base pair forms a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In DNA base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.
Structure
Adenine forms several tautomers, compounds that can be rapidly interconverted and are often considered equivalent.
Biosynthesis
Purine metabolism involves the formation of adenine andguanine. Both adenine and guanine are derived from the nucleotide inosine monophosphate (IMP), which is synthesised on a pre-existing ribosome through a complex pathway using atoms from the amino acids glycine,glutamine, and aspartic acid, as well as fused with the enzyme tetrahydrofolate.
In Saccharomyces cerevisiae, (yeast), the adenine pathwayconverts P-ribosyl-PP into adenine through a seven step process.
Function
Adenine is one of the two purine nucleobases (the other being guanine) used in forming nucleotides of the nucleic acids. In DNA, adenine binds to thymine via two hydrogen bonds to assist in stabilizing the nucleic acid structures. In RNA, which is used for protein synthesis, adenine binds touracil.
Adenine forms adenosine, a nucleoside, when attached toribose, and deoxyadenosine when attached to deoxyribose. It forms adenosine triphosphate (ATP), a nucleotide, when three phosphate groups are added to adenosine. Adenosine triphosphate is used in cellular metabolism as one of the basic methods of transferring chemical energy between chemical reactions.
History
In older literature, adenine was sometimes called Vitamin B4. It is no longer considered a true vitamin or part of the Vitamin B complex. However, two B vitamins, niacin and riboflavin, bind with adenine to form the essential cofactors nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide(FAD), respectively. Hermann Emil Fischer was one of the early scientists to study adenine.
0 Response to "Adenine"