Role of boundary constraints in DNA cyclization

We modify the classical Shimada-Yamakawa theory of DNA looping by generalizing the form of boundary constraints. This generalization is important in the context of DNA cyclization experiments since it mimics the reduced local rigidity of the "nicked" DNA loop. Our results indicate that the non-trivial boundary constraints may be responsible for the existing dramatic discrepancy between various DNA cyclization experiments. The developed effective Hamiltonian method may be further extended to a broad class of DNA looping problems.