Before revision:  For A-DNA it is approximately 28 deg., and for B-DNA  approximately 38 deg., in accord with the principle of optimal packing of tubular double helices .
After revision:  For A-DNA it is approximately 28 deg., and for B-DNA approximately 38 deg., less than the corresponding zero-twist angle of 41.8 deg., which is consistent with the suggested principle for transcription .