Before revision: In vivo, DNA forms loops over a broad range of length scales: from several thousand base pairs (bp) down to about 100 bp. In loops shorter than the DNA persistence length (150 bp), thermal fluctuations can be neglected, and the molecule assumes approximately its minimal-energy shape. It is well-known that for a simple isotropic wormlike chain model, the minimal-energy shape of a loop can be derived exactly and is expressed as a combination of inverse elliptic integrals.
After revision: In vivo, DNA forms loops over a broad range of length scales: from several thousand base pairs (bp) . We show that in these loops the minimal-energy shape of a loop can be derived exactly and is expressed as a combination of inverse elliptic integrals.