Informatics Publishing Limited

S. N. Upadhyay ¹, Rampal Singh ¹, A. K. Gupta ¹, A. Ghose ¹

Affiliations
1 Radiation Biology Division, Institute of Nuclear Medicine and Allied Sciences, Lucknow Road, Delhi 110007, IN

Abstract

The absorption value for reconstituted DNH is less than that of DNA in the X-peak in the unirradiated state. For Y-peak, intensity of absorption is lower for DNA and those for H₃-histone and reconstituted DNH am same. With increasing pH, hyperchromicity of H₃-histone slowly increases indicating unfolding of peptide bonds with increasing pH. Consideration of Y/X ratio reveals that the degree of denaturation by gamma irradiation has been more for DNA as compared to reconstituted DNH for the same irradiation dose. Thus protection of DNA against radiation has been noted due to presence of H₃-histone. Denaturation with radiation has been found to be more for DNH reconstituted after irradiation as compared to that of DNH reconstituted before irradiation.

Keywords

DNA, Histone, Reconstituted DNH, Gamma Irradiation.

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S. N. Upadhyay ¹, Rampal Singh ¹, A. Ghose ¹

Affiliations
1 Radiation Biology Department, Institute of Nuclear Medicine & Allied Sciences, Lucknow Road, Delhi-110054, IN

Abstract

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.

Keywords

Binding Ratio Protector 5-Hydroxy-L-Tryptophan.

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