Study of Mn2+ ion influence on DNA at increased temperatures

Complexes of calf thymus DNA with Mn2+ ions were studied at 45 degrees C in water solution by means of IR spectroscopy. It was revealed that the proce ss of Mn2+ ion binding both to phosphate groups and to nitrogen bases of DN A has a highly cooperative character. It was found that the intensity of IR absorption bands increases with increasing of Mn2+ ion concentration, has a maximum, and does not have a saturation region. Process of DNA sedimentat ion has occurred at high Mn2+ ion concentration. Nevertheless, DNA has rema ined in the frame of B-form family during the whole binding process and aft er the sedimentation.