Crystal morphology of precipitated mannan

Bittiger, H.; Husemann, E.

doi:10.1002/pol.1972.110100507

Cited by 19 publications

(23 citation statements)

References 4 publications

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“…A t present, this description accounts well for the morphology of the pseudo-fibrillar precipitate found with T. salep or A. konjac glucomannan (Figs. [6][7][8].…”

Section: Morphology Of the Glucomannan Crystalsmentioning

confidence: 99%

“…A few reports have dealt with the morphological and structural features of pure mannan poly(1 -4)-P-D-mannose in both its native and recrystallized Two polymorphs of this polysaccharide have been characterized: mannan I and mannan 11, as defined by Frei and P r e s t~n .~ The former is found both in the native state or during recrystallization, whereas the latter does not occur in nature and is obtained either by swelling in alkali4 or by recrystallization. 6 Why mannan will recrystallize in the form of mannan I under certain conditions or mannan I1 in other cases is not well understood.…”

Section: Introductionmentioning

confidence: 99%

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Crystallization behavior of glucomannan

et al. 1982

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SynopsisFive different glucomannan samples were recrystallized from dilute solution. Depending on the experimental conditions, the crystals obtained could be identified as corresponding to the mannan I (anhydrous precipitate of more or less regular lozenge-shaped crystals) or mannan I1 (hydrated gel-forming pseudo-fibrillar precipitate). High-molecular-weight material, low temperature of crystallization, or a polar crystallization medium favored the mannan I1 polymorph, whereas a low-molecular weight, a high temperature of crystallization, and a crystallization medium of low polarity yielded the mannan I polymorph. Since the base-plane unit-cell dimensions are fairly constant with respect to variation of glucose, it is likely that isomorphous replacement of mannose by glucose occurs in glucomannan crystallization; the data also indicate that perfection of the glucomannan crystals was reduced in specimens having a high g1ucose:mannose ratio. The oriented crystallization of glucomannan on cellulose microfibrils was also studied under conditions where the mannan I polymorph was obtained. This gave shish-kebab structures that were characterized.

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“…A t present, this description accounts well for the morphology of the pseudo-fibrillar precipitate found with T. salep or A. konjac glucomannan (Figs. [6][7][8].…”

Section: Morphology Of the Glucomannan Crystalsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crystallization behavior of glucomannan

et al. 1982

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“…When, for instance, low-molecular-weight mannan from seed endosperm is recrystallized from solution, it invariably yields the mannan I polymorph, identical to the native mannan.3,4 This contrasts with cellulose, which in similar conditions yields cellulose II. 5,6 This difference in behavior is intriguing and needs further investigation, especially by preparing well-characterized entities such as lamellar single crystals or fibers.…”

Section: Introductionmentioning

confidence: 98%

Single crystals and oriented crystallization of ivory nut mannan

et al. 1979

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SynopsisThe preparation of lamellar single crystals of mannan[poly((l -4)-P-D-mannose)] is described. Electron diffractograms clearly identify the perpendicular orientation of the chain axis with respect to the lamellar surface. Since the degree of polymerization is 40 or less, no conclusion is made as to chain folding. The unit cell corresponds to the mannan I structure derived from x-ray fiber data on oriented algal mannan. The baseplane dimensions found were a = 7.22 8 and b = 8.92 8, and the systematic absences observed confirm the proposed P212121 group. It was found that cellulose microfibrils from Valonia uentricosa and bacterial cellulose could serve as extended chain nuclei for inducing oriented crystallization of mannan on cellulose. This produces a shish-kebab type of morphology.

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“…With such questions in mind, the present study was devised to see how selected mannanases could interact with well characterized mannan samples. For this, we have prepared suspensions of single crystals of linear low molecular mass mannan I [10–12]. This allomorph was selected as it is one of the most dense polysaccharide structures known and it does not contain any water in its crystalline lattice [13–16]; therefore it should be particularly hard to digest.…”

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confidence: 99%

Digestion of single crystals of mannan I by an endo‐mannanase from Trichoderma reesei

Sabini

Wilson

Siika‐aho³

et al. 2000

European Journal of Biochemistry

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The enzymatic degradation of single crystals of mannan I with the catalytic core domain of a b-mannanase (EC 3.2.1.78 or Man5A) from Trichoderma reesei was investigated by transmission electron microscopy and electron diffraction. The enzyme attack took place at the edge of the crystals and progressed towards their centres. Quite remarkably the crystalline integrity of the crystals was preserved almost to the end of the digestion process. This behaviour is consistent with an endo-mechanism, where the enzyme interacts with the accessible mannan chains located at the crystal periphery and cleaves one mannan molecule at a time. The endo mode of digestion of the crystals was confirmed by an analysis of the soluble degradation products.

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Crystal morphology of precipitated mannan

Cited by 19 publications

References 4 publications

Crystallization behavior of glucomannan

Crystallization behavior of glucomannan

Single crystals and oriented crystallization of ivory nut mannan

Digestion of single crystals of mannan I by an endo‐mannanase from Trichoderma reesei

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