A Comparative Study of Native and Reconstituted Nucleoprotamine under Different Denaturing Agents

Protamine showed a linear response with concentration so far as absorbance is concerned at 210 nm and 230 nm in the concentration range of 2-20 × 10^-5 g/ml. Isoelectric point of reconstituted DNP has been found to be at pH 3.25. On storage, relative absorbance values for DNP varied inversely with concentration. With storage or heat-denaturation, the relative absorbance values for native and reconstituted DNP were similar. The degree of denaturation for both were maximum for heat-denatured samples, followed by storage. With increasing radiation dose, Y-peak values were found to increase consistently for DNA, Protamine, Native and reconstituted DNP. The relative changes in X-peak were comparatively less for all of them. The -C=C-C=C- chromophores of DNA were released in solution as a function of dose whereas -C=C-C=N- chromophores were less released for the same dose range. The changes in protamine with radiation dose occur due to increased chromophoricities of imidazole, tyrosine, histidine and tryptophan. Y-peak values of reconstituted DNP were more comparable to the native DNP. This is due to the increased contribution from protamine as they remain loosely bound to DNA. X-peak values are comparable for the native and the reconstituted DNP; the changes are occurring in DNA whose concentration remains the same in both the cases.