[Theory of DNA melting in the interval of B-A transition].
Theory of DNA melting within the B--A transition range is presented. The phase diagram in coordinates alcohol--temperature is plotted. The temperature shift of DNA helix--coil transition in the B--A transition point is predicted to be delta T = 3 degrees. The temperature rise of DNA melting in the range of B--A transition is caused by the presence of junctions between regions in B and A forms in helical sections.