Does quantum entanglement in DNA synchronize the catalytic centers of   type II restriction endonucleases?
  Several living systems have been examined for their apparent optimization of structure and function for quantum behavior at biological length scales. Orthodox type II endonucleases, the largest class of restriction enzymes, recognize four-to-eight base pair sequences of palindromic DNA, cut both strands symmetrically, and act without an external metabolite such as ATP. While it is known that these enzymes induce strand breaks by attacking phosphodiester bonds, what remains unclear is the mechanism by which cutting occurs in concert at the catalytic centers. Previous studies indicate the primacy of intimate DNA contacts made by the specifically bound enzyme in coordinating the two synchronized cuts. We propose that collective electronic behavior in the DNA helix generates coherent oscillations, quantized through boundary conditions imposed by the endonuclease, that provide the energy required to break two phosphodiester bonds. Such quanta may be preserved in the presence of thermal noise and electromagnetic interference through decoherence shielding, the specific complex's exclusion of water and ions surrounding the helix. Clamping energy imparted by the enzyme decoherence shield is comparable with zero-point modes of the dipole-dipole oscillations in the DNA recognition sequence. The palindromic mirror symmetry of this sequence should conserve parity during the process. Experimental data corroborate that symmetric bond-breaking ceases when the symmetry of the endonuclease complex is violated, or when environmental parameters are perturbed far from biological optima. Persistent correlation between states in DNA sequence across spatial separations of any length--a characteristic signature of quantum entanglement--may be explained by such a physical mechanism. 
P. Kurian, G. Dunston, J. Lindesay
physics.bio-ph q-bio.BM quant-ph