Electron diffraction study on the two crystalline phases occurring in native cellulose from an algal cell wall

Abstract

Cellulose from the cell wall of the green alga Microdictyon tenuius was studied by electron diffraction. The diffractograms disclose two distinct crystalline phases. The major phase has a one-chain, triclinic (PI) structure with unit cell parameters of a = 0.674 nm, b = 0.593 nm, c (chain axis) = 1.036 nm, a = 117°, 0 = 113°, and y = 81°. The crystal unit cell of the minor component has two chains and is monoclinic (P2i), with a -0.801 nm, b = 0.817 nm, c (chain axis) = 1.036 nm, and y the monoclinic angle = 97.3°. The triclinic phase is metastable, and annealing it in dilute alkali at 260 °C converts it into the monoclinic form. The presence of two phases in Microdictyon can be extended to other algal celluloses and is consistent with the biphasic character deduced from 13C CP/MAS NMR spectroscopy. The triclinic and the monoclinic structures correspond to the la and Id spectra, respectively.

The binding specificity and affinity determinants of family 1 and family 3 cellulose binding modules

“…Consistent with earlier investigations (7,12,25,26), our current data confirm that tryptophan residues contribute higher energy of binding than tyrosines on a CBM binding surface. However, the effect is limited to one Trp residue; addition of two Trp residues led to no further improvement in binding.…”

“…Schematic presentation of the organization of the cellulose chains in the I ␣ allomorph of cellulose crystals and the shape of the complete crystal formed. As their unit cell parameters have been determined, Valonia crystals are known to be primarily in the I ␣ form (12) and the corresponding indexing is thus used throughout this article. The d-spacings characteristic to the different crystalline planes are indicated.…”

“…Valonia cellulose crystals occur predominantly as cellulose I ␣ with triclinic unit cells (12). Two of the four crystal faces, the (100) and (010) faces, present relatively large, hydrophilic surfaces rich in OH groups (Fig.…”

Modelling of Congo red adsorption on the hydrophobic surface of cellulose using molecular dynamics

“…At the ultrastructural level, this statement is supported by recording of high-resolution details of large highly crystalline microfibrils such as those of Valonia, tunicin, Micrasterias etc. Indeed, the analysis of their cross-sections by electron diffraction and diffraction contrast electron microscopy, including lattice imaging, clearly indicates that their surface corresponds to either the (1 1 0) and (1 -1 0) planes of the monoclinic cellulose Ib lattice or the (1 0 0) and (0 1 0) of its triclinic Ia counterpart (Sugiyama et al 1991), which are rich in hydrophilic OH moieties (Sugiyama et al 1985;Revol 1982;Helbert et al 1998;Kim et al 1996). Observations of Valonia surface at near atomic resolution by AFM is in agreement with the TEM results as they definitely show organized arrays of surface hydroxymethyl groups within the Ia phase of Valonia cellulose (Baker et al 1997(Baker et al , 2000.…”

Supra-Molecular Structure and Chemical Reactivity of Cellulose I Studied Using CP/MAS 13C-NMR

“…A conversion factor of 0.57nm width per cellulose polymer has been used in the calculations [35][36][37]. The final 91%, 92% and 96% -cellulose dissolving pulp samples were initially run on the CP/MAS 13 C-NMR in the wet state (never dried).…”