The effect of cooperativity on hydrogen bonding interactions in native cellulose I beta from ab initio molecular dynamics simulations

Hydrogen bonding cooperativity plays an important role in the stability of alpha-helices, beta-sheets and many other hydrogen bonding systems. Here ab initio calculations were performed to determine the cooperative effect on hydrogen bonding structures in native crystalline cellulose I beta. Both isolated and paired cellulose chains with degree of polymerisation varying from 2 to 7 were investigated. A highly cooperative hydrogen bonding interaction was found in the paired cellulose chains, particularly between the inter-chain and intra-chain hydrogen bonds. An enhancement in hydrogen bonding strength was also observed when infinite cellulose chains were paired to form cellulose sheets, and when cellulose sheets were stacked to form three dimensional cellulose crystalline structures. This hydrogen bonding cooperativity is likely due to the electron delocalisation effect.