Dear Gangula,

As you know, each strand of DNA is built from a sequence of four different nuclotide monomers consisting of a deoxyribose sugar, phosphate groups, and a nitrogenous base conventionally identified by the letters A,T, C and G. DNA itself consists of two of these polynuclotide chains that are coiled around a common axis in a configuration something like the protein alpha helix. The sugar-and-phosphate backbones are on the outiside so that the nucleotide bases are on the inside and facing each other. The two strands are held together by hydrogen bonds that link a nitrogen atom of a nucleotide in one chain with a nitrogen or oxygen on the nucleotide that is across from it on the other chain. This unique assembly provides an efficient hydrogen bonding within this configuration and can only occur between the pairs A-T and C-G. Water molecules, hydrogen-bonded to the outer parts of the DNA helix and help stabilize it.

In the case where A, T, C and D are dissolved separably in a water as a medium (the assembly of A-T and C-D in the helix is destroyed) the interactions between the water molecules and each of A, T, C or D will be much higher than between A and T, and C and D. It is a question of energy balance and competition. The energy of the system is expected to be at minimum when each of A, T, C or D is surrounded by water molecules and NOT when A binds to T and C to G.

Hoping this will be helpful,

Rafik

Thank you very much Mr. Rafik. The answer was very elaborate and helpful. So , it is not possible to capture guanosine from a sample via a cytosine moeity attached to a nanoparticles through H bonding ? Do you have any suggestions ?

Dear Gangula,

Please read the attached publication.

Hoping this will be helpful,

Rafik

Thank you Dear Rafik. Will read the attached article.