Interaction of 5-Hydroxy-L-Tryptophan with Deoxyribonucleic Acid and Nucleohistone

The binding of 5-hydroxy-L-tryptophan (HT), a radioprotector, with deoxyribonucleic acid (DNA) and deoxyribonucleohistone (DNH) in 2.5 × 10^-4 MEDTA and 0.9% sodium chloride solutions takes place in the concentration ratio of (a) DNA : HT 25μg/ml : 20-25 μg/ml and (b) DNH : HT 25 μg/ml : 20-25 μg/ml. Analytical evidences show that the modes of binding are by (i) electrostatic interaction (ii) ion condensation (iii) staking and (iv) intercalation. The two solvents EDTA and 0.9% sodium chloride affect the degree of dissociation of DNA and DNH to different extent, and hence attachment mode of HT with these bioplaymers is decided by stereospecific accessibility. The functional groups responsible for binding are phenolic OH,(indole), (side chain of HT), phosphate groups and phosphodiester bond for DNA, and CONH group, lysine and arginine and chromophores like: -C=C-C=N and -C=C-C=O for DNH. The method of calculations of the binding has been given.