Paracrystalline lattice disorder in cellulose. I. Reappraisal of the application of the two‐phase hypothesis to the analysis of powder x‐ray diffractograms of native and hydrolyzed cellulosic materials

Kulshreshtha, A. K.; Dweltz, N. E.

doi:10.1002/pol.1973.180110307

Cited by 39 publications

(23 citation statements)

References 18 publications

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“…the sum of the peak intensity and the amorphous background). Our values of crystal size and crystallinity obtained with bacterial cellulose are in agreement with the data in the literature (48,49).…”

Section: Determination Of the Yield Of In Vitro Synthesis Of Cellulossupporting

confidence: 81%

“…This shift is small but nevertheless meaningful. Indeed, several x-ray analyses of cellulose samples that were systematically decrystallized showed that the creation of defects induces a shift of the 200 diffraction peak toward higher d-spacings, indicating some swelling of the cellulose unit cell along its a axis (48,66,67). In light of these data, a comparison of traces A and B in Fig.…”

Section: Discussionmentioning

confidence: 99%

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In Vitro Versus in VivoCellulose Microfibrils from Plant Primary Wall Synthases: Structural Differences

Lai-Kee-Him¹,

Chanzy²,

Müller³

et al. 2002

Journal of Biological Chemistry

148

101

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Detergent extracts of microsomal fractions from suspension cultured cells of Rubus fruticosus (blackberry)were tested for their ability to synthesize in vitro sizable quantities of cellulose from UDP-glucose. Both Brij 58 and taurocholate were effective and yielded a substantial percentage of cellulose microfibrils together with (133)-␤-D-glucan (callose). The taurocholate extracts, which did not require the addition of Mg 2؉ , were the most efficient, yielding roughly 20% of cellulose. This cellulose was characterized after callose removal by methylation analysis, electron microscopy, and electron and x-ray synchrotron diffractions; its resistance toward the acid Updegraff reagent was also evaluated. The cellulose microfibrils synthesized in vitro had the same diameter as the endogenous microfibrils isolated from primary cell walls. Both polymers diffracted as cellulose IV I , a disorganized form of cellulose I. Besides these similarities, the in vitro microfibrils had a higher perfection and crystallinity as well as a better resistance toward the Updegraff reagent. These differences can be attributed to the mode of synthesis of the in vitro microfibrils that are able to grow independently in a neighbor-free environment, as opposed to the cellulose in the parent cell walls where new microfibrils have to interweave with the already laid polymers, with the result of a number of structural defects.

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Section: Determination Of the Yield Of In Vitro Synthesis Of Cellulossupporting

confidence: 81%

Section: Discussionmentioning

confidence: 99%

In Vitro Versus in VivoCellulose Microfibrils from Plant Primary Wall Synthases: Structural Differences

Lai-Kee-Him¹,

Chanzy²,

Müller³

et al. 2002

Journal of Biological Chemistry

148

101

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“…13 C-CP/MAS Spectra of Cellulose-The relative crystallinities, determined by x-ray diffraction, of Valonia cellulose (from Valonia ventricosa), BMCC, and Avicel are 1.0, 0.76, and 0.50, respectively (13,20). The crystallinity of PASC is unknown, but it is expected to be less than that of Avicel because of the exposure to acid during its preparation.…”

Section: Resultsmentioning

confidence: 99%

Carbohydrate-binding Modules Recognize Fine Substructures of Cellulose

McLean¹,

Boraston²,

Brouwer³

et al. 2002

Journal of Biological Chemistry

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“…In the experimental part, we used BMCC as one of the least heterogeneous celluloses with clearly expressed crystalline character [25]. The [ 3 H]-reduced cellulose was employed for these studies because this derivatisation procedure does not significantly influence the mode of action of cellulases on oligosaccharides [10].…”

Section: Discussionmentioning

confidence: 99%

Progress curves

Nutt

Sild²,

Pettersson³

et al. 1998

European Journal of Biochemistry

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The chain-end preference and processivity of the cellulases 1,4-β-D-glucan-cellobiohydrolase I (CBH I) and 1,4-β-D-glucan-cellobiohydrolase II (CBH II) from Trichoderma reesei and 1,4-β-D-glucancellobiohydrolase 50 (CBH 50) and 1,4-β-D-glucan-cellobiohydrolase 58 (CBH 58) from Phanerochaete chrysosporium were studied by comparing experimental degradation data on reducing end-labelled bacterial microcrystalline cellulose with computer simulations of different models. Our results with T. reesei and P. chrysosporium cellulases show that there is a common pattern of hydrolysis for CBH-I-type enzymes and another clearly distinguishable pattern for CBH-II-type enzymes, especially in the initial part of the progress curve.Keywords : cellulase ; cellulose; hydrolysis ; simulation ; mode of action.In nature, the breakdown of cellulose is carried out mainly by fungi and bacteria. These organisms degrade crystalline cellulose by means of several enzymes acting at the ends (exocellulases) or randomly (endoglucanases) on the cellulose chains. Cellulases, like many other enzymes attacking insoluble or 'larger-than-enzyme' polymeric substrates, have a characteristic two-domain organisation : a catalytic domain connected by a flexible linker to a separate cellulose-binding domain [1]. Effective degradation of native cellulose requires cooperation between different functional types of cellulases and displays two distinctive modes of synergism; namely, cooperation among endoglucanases and cellobiohydrolases (CBHs) (endo/exo synergism), where the endoglucanases are supposed to create a large number of free ends susceptible to exoglucanase action [2Ϫ4], and cooperation among different CBHs [5Ϫ7]. The molecular basis for this latter synergism is not yet understood, mainly because the modes of action of the individual enzymes on crystalline cellulose are not known. By definition, CBHs attack the cellulose chain from the non-reducing end [8]. Recent data indicate, however, that the exhaustively studied Trichoderma reesei 1,4-β-D-glucan-cellobiohydrolase I (CBH I) preferentially attacks the reducing end of cellooligosaccharides, whereas the similarly well-characterised 1,4-β-D-glucan-cellobiohydrolase II (CBH II) from the same organism indeed prefers the non-reducing end [9,10].

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Paracrystalline lattice disorder in cellulose. I. Reappraisal of the application of the two‐phase hypothesis to the analysis of powder x‐ray diffractograms of native and hydrolyzed cellulosic materials

Cited by 39 publications

References 18 publications

In Vitro Versus in VivoCellulose Microfibrils from Plant Primary Wall Synthases: Structural Differences

In Vitro Versus in VivoCellulose Microfibrils from Plant Primary Wall Synthases: Structural Differences

Carbohydrate-binding Modules Recognize Fine Substructures of Cellulose

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