Refinement of the structure of β‐chitin

Abstract

The structure of β‐chitin has been refined by rigid‐body least‐squares methods, based on the intensity data for highly crystalline specimens from the pogonophore Oligobrachia ivanovi. The structure consists of an array of poly‐N‐acetyl‐D‐glucosamine chains all having the same sense, which are linked together in sheets by NH … OC hydrogen bonding of the amide groups. In addition to the O‐3′H … O‐5 intramolecular hydrogen bond, analogous to that in cellulose, the CH 2 OH side chain forms an intrasheet hydrogen bond to the carbonyl oxygen on the next chain. This structure shows considerably better agreement between observed and calculated intensities than that possessing an intersheet hydrogen bond, as had been proposed previously. The structure is consistent with the swelling properties of β‐chitin and can also be seen to be analogous to that of native cellulose.