ABSTRACT
I. INTRODUCTION DNA in aqueous solution carries a very high negative charge, with two electronic charges per base pair (or equivalently, per 3.4 A) along the length of the double helix. In its unpackaged form, DNA is well described as a wormlike chain with a persistence length of approximately 500 A [1]. How ever, when DNA is packaged in viruses and cells, it is highly concentrated into configurations where helices are approximately parallel to each other with a surface-to-surface separation of roughly 5 A. For example, the DNA of the T7 bacteriophage is approximately 10“4 times smaller in the phage head than in its unpackaged form [2]. To concentrate DNA to this level by brute force would require a pressure of over 100 atm [3].
