Crystalline morphology of Valonia macrophysa cellulose IIII revealed by direct lattice imaging

Sugiyama, Junji; Harada, Hiroshi; Saiki, Hiroshi

doi:10.1016/0141-8130(87)90039-0

Cited by 32 publications

(27 citation statements)

References 23 publications

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“…These results can be interpreted as indicating that the reason for the higher cellobiose production from cellulose I β ′ than cellulose I β is the larger amount of adsorption during hydrolysis, but not an increase in specific activity. There are several studies showing that conversion into cellulose III I decreases the crystal size [22,23]. Therefore, treatment with supercritical ammonia increases the surface area available for cellobiohydrolase (possibly the hydrophobic surface) and thus increases the number of enzyme molecules that can be adsorbed on the surface of cellulose III I and I β ′ (Fig.…”

Section: Discussionmentioning

confidence: 99%

Activation of crystalline cellulose to cellulose III_I results in efficient hydrolysis by cellobiohydrolase

2007

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Cellulose is a linear polymer of b-1,4-linked anhydrous glucose residues, and is the major component of plant cell walls. In nature, cellulose chains are packed into ordered arrays to form insoluble microfibrils, which are stabilized by cross-links involving intermolecular hydrogen bonds. Microfibrils generally consist of a mixture of disordered amorphous cellulose and cellulose I, which forms highly ordered crystalline regions. Cellulose I is further classified into two polymorphs, triclinic cellulose I a , which is found in algal and bacterial celluloses, and monoclinic cellulose I b, called cotton-ramie-type cellulose [1][2][3]. Although the differences in their physiological roles in the cell wall are uncertain, cellulose I a is more susceptible than cellulose I b to hydrolysis by cellulase [4,5].Cellulase is a generic term for enzymes hydrolyzing b-1,4-glucosidic linkages. If we consider the structure of microfibrils, however, cellulases should be subdivided into two categories, as all cellulases can hydrolyze amorphous cellulose, whereas only a limited number can hydrolyze crystalline cellulose [6]. The enzymes that hydrolyze crystalline cellulose are generally called cellobiohydrolases, and share similar twodomain structures, with a catalytic domain (CD) and a cellulose-binding domain (CBD) [7][8][9][10]. As the initial step of the reaction, they are adsorbed on the surface of crystalline cellulose via the CBD, then glucosidic linkages are hydrolyzed by the CD. As the reaction produces mainly cellobiose, a soluble b-1,4-glucosidic dimer, from insoluble substrates, the hydrolysis of crystalline cellulose occurs at a solid ⁄ liquid interface [11][12][13]. To evaluate such reactions, we recently developed a novel analysis based on surface density (q), defined as the amount of adsorbed enzyme (A) divided by the maximum adsorption of the enzyme (A max ) [14]. Using this parameter, we were able to analyze the hydrolysis of crystalline cellulose while taking account of the available substrate The crystalline polymorphic form of cellulose (cellulose I a -rich) of the green alga, Cladophora, was converted into cellulose III I and I b by supercritical ammonium and hydrothermal treatments, respectively, and the hydrolytic rate and the adsorption of Trichoderma viride cellobiohydrolase I (Cel7A) on these products were evaluated by a novel analysis based on the surface density of the enzyme. Cellobiose production from cellulose III I was more than 5 times higher than that from cellulose I. However, the amount of enzyme adsorbed on cellulose III I was less than twice that on cellulose I, and the specific activity of the adsorbed enzyme for cellulose III I was more than 3 times higher than that for cellulose I. When cellulose III I was converted into cellulose I b by hydrothermal treatment, cellobiose production was dramatically decreased, although no significant change was observed in enzyme adsorption. This clearly indicates that the enhanced hydrolysis of cellulose III I is related to the structure of the crystalline...

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Section: Discussionmentioning

confidence: 99%

Activation of crystalline cellulose to cellulose III_I results in efficient hydrolysis by cellobiohydrolase

2007

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“…When immersed into ethylenediamine, followed by washing in methanol, the samples became converted into the cellulose IIII allomorph. This transition, which could be visualized by bright and dark-field (Roche and Chanzy, 1981;Chanzy et al, 1986) or lattice imaging (Sugiyama et al, 1987) showed how the large initial crystals of Valonia were broken into much smaller ones, which thus became accessible to further chemical transformation.…”

Section: Cellulose Allomorphs Seen By Temmentioning

confidence: 99%

Transmission electron microscopy of cellulose. Part 1: historical perspective

2018

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Following the first electron micrographs of cotton in 1940, the development of transmission electron microscopy applied to native cellulose has been evolving in a series of successive advances. At first, faced with the weak contrast of the early images, the operators had to use specific electron dense contrasting agents to reveal the ultrastructure of their samples.It was thus found that all native celluloses consisted of microfibrils, with some size variations depending on the sample origin. Following this, a major advance was achieved when the electron microscopes could be adjusted with low electron doses, allowing the recording of diffraction diagrams from the electron beam-sensitive cellulose samples. Under these conditions, one could obtain information of cellulose itself and not, as before, of the contrasting agent. This important development applied to microdiffraction conditions revealed that some large cellulose microfibrils could yield spot diagrams typical of single crystals. Their recording led to a decisive progress for resolving the molecular and crystal structure of the two cellulose allomorphs, cellulose Ia and Ib. Using various combinations of diffracted beams to create the images, the so called "diffraction contrast images" could then be developed. These micrographs showed many aspects of the crystalline core of cellulose, including spectacular high-resolution images showing the molecular planes of cellulose in their crystalline environment. Today, electron diffraction, diffraction contrast imaging and low-dose electron microscopy have become major tools to follow the effect of various physical, chemical and biochemical processes at the cellulose crystalline level.

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“…Preparing cellulose III I from cellulose I involves fracturing of the crystal structure (Roche and Chanzy 1981), particularly between adjacent 1 " 10 ð Þ planes (Sugiyama et al 1987). Simulations were designed to test extreme cases, in which cellulose I b crystals were fractured all the way to nanocrystals comprising individual 1 " 10 ð Þ or (110) planes.…”

Section: Diffractograms From Single Planesmentioning

confidence: 99%

Simulation of X-ray diffractograms relevant to the purported polymorphs cellulose IVI and IVII

Newman

2008

Cellulose

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Diffractograms were simulated for model nanocrystals of cellulose I b , using numerical summation of radiation scattered from all carbon and oxygen atoms in the nanocrystal. Diffractogram peaks were sometimes displaced by a few degrees from positions calculated by the Bragg equation, as predicted in a published study based on a different mathematical approach. Simulated diffractograms showed 2 or 3 peaks, depending on the crosssectional size and shape of the model nanocrystal. Some of the 2-peak diffractograms resembled published results for the purported polymorph cellulose IV I , or for cell-wall cellulose, supporting suggestions that cellulose IV I is simply cellulose I fragmented into nanocrystals with relatively small cross-sectional dimensions. A published diffractogram for cellulose IV II could not be simulated with acceptable precision, suggesting that this polymorph might have a crystal structure distinctly different from that of cellulose I b .

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Crystalline morphology of Valonia macrophysa cellulose IIII revealed by direct lattice imaging

Cited by 32 publications

References 23 publications

Activation of crystalline cellulose to cellulose III_I results in efficient hydrolysis by cellobiohydrolase

Activation of crystalline cellulose to cellulose III_I results in efficient hydrolysis by cellobiohydrolase

Transmission electron microscopy of cellulose. Part 1: historical perspective

Simulation of X-ray diffractograms relevant to the purported polymorphs cellulose IVI and IVII

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Crystalline morphology of Valonia macrophysa cellulose IIII revealed by direct lattice imaging

Cited by 32 publications

References 23 publications

Activation of crystalline cellulose to cellulose IIII results in efficient hydrolysis by cellobiohydrolase

Activation of crystalline cellulose to cellulose IIII results in efficient hydrolysis by cellobiohydrolase

Transmission electron microscopy of cellulose. Part 1: historical perspective

Simulation of X-ray diffractograms relevant to the purported polymorphs cellulose IVI and IVII

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Activation of crystalline cellulose to cellulose III_I results in efficient hydrolysis by cellobiohydrolase

Activation of crystalline cellulose to cellulose III_I results in efficient hydrolysis by cellobiohydrolase