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The helical structure of cellulose I
Author(s) -
Viswanathan A.,
Shenouda S. G.
Publication year - 1971
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1971.070150302
Subject(s) - cellobiose , cellulose , crystallography , molecule , chemistry , crystal structure , helix (gastropod) , zonal and meridional , crystal (programming language) , residue (chemistry) , monoclinic crystal system , cellulase , organic chemistry , physics , biology , ecology , atmospheric sciences , snail , computer science , programming language
The unit cell dimension along the crystallographic b ‐axis of cellulose is widely accepted to be 10.3 Å, as against the distance of 10.3912 Å between the terminal oxygen atoms of a cellobiose molecule, estimated from the now well‐established crystal structure of cellobiose. Since cellulose is only a polymer of the cellobiose residue, it has been possible to derive the crystal structure of cellulose I from that of cellobiose. The strict application of stereochemical principles to the sucessive residues in the cellulose chain and a consideration of the formal geometric characteristics of a helix suggest a helical form to the cellulose molecule, with seven cellobiose residues per turn, radius r = 1.5830 Å, and angle of helix 7°51′ which is close to the x‐ray orientation angle of 8°21′ observed in ramie, the best‐oriented native cellulose. An analysis of intensity data both for the equatorial and for the meridional reflections leads to a unit cell with central reversed and corner chains and a relative shift between them of one fourth of the repeat length along the b ‐axis.