Preparation of Cellouronic Acids and Partially Acetylated Cellouronic Acids by TEMPO/NaClO Oxidation of Water-Soluble Cellulose Acetate

Gomez-Bujedo, Silvia; Fleury, Étienne; Vignon, M.R.

doi:10.1021/bm034405y

Cited by 72 publications

(62 citation statements)

References 24 publications

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“…Cellulose acetate with approximately 0.5-1.0 acetyl groups per Glc residue is water soluble (Gomez-Bujedo et al, 2004). Because of the method of preparation, most of the -CO.CH 3 groups in our WSCA would be attached to position 6 of the Glc residues, like the xylose residues of xyloglucan.…”

Section: Water-soluble Cellulose Acetate and Other Artificial Donor-smentioning

confidence: 99%

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Mixed‐linkage β‐glucan : xyloglucan endotransglucosylase, a novel wall‐remodelling enzyme from Equisetum (horsetails) and charophytic algae

Fry¹,

Mohler²,

Nesselrode³

et al. 2008

The Plant Journal

106

135

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SummaryMixed-linkage (1 fi 3,1 fi 4)-b-D-glucan (MLG), a hemicellulose long thought to be confined to certain Poales, was recently also found in Equisetum; xyloglucan occurs in all land plants. We now report that Equisetum possesses MLG:xyloglucan endotransglucosylase (MXE), which is a unique enzyme that grafts MLG to xyloglucan oligosaccharides (e.g. the heptasaccharide XXXGol). MXE occurs in all Equisetum species tested (Equisetum arvense, Equisetum fluviatile, Equisetum hyemale, Equisetum scirpoides, Equisetum telmateia and Equisetum variegatum), sometimes exceeding xyloglucan endotransglucosylase (XET) activity. Charophytic algae, especially Coleochaete, also possess MXE, which may therefore have been a primordial feature of plant cell walls. However, MXE was negligible in XET-rich extracts from grasses, dicotyledons, ferns, Selaginella and bryophytes. This and the following four additional observations indicate that MXE activity is not the result of a conventional xyloglucan endotransglucosylase/hydrolase (XTH): (i) XET, but not MXE, activity correlates with the reaction rate on water-soluble cellulose acetate, hydroxyethylcellulose and carboxymethylcellulose, (ii) MXE and XET activities peak in old and young Equisetum stems, respectively, (iii) MXE has a higher affinity for XXXGol (K m $ 4 lM) than any known XTH, (iv) MXE and XET activities differ in their oligosaccharide acceptor-substrate preferences. High-molecular-weight (M r ) xyloglucan strongly competes with [ 3 H]XXXGol as the acceptor-substrate of MXE, whereas MLG oligosaccharides are poor acceptor-substrates. Thus, MLGto-xyloglucan grafting appears to be the favoured activity of MXE. In conclusion, Equisetum has evolved MLG plus MXE, potentially a unique cell wall remodelling mechanism. The prominence of MXE in mature stems suggests a strengthening/repairing role. We propose that cereals, which possess MLG but lack MXE, might be engineered to express this Equisetum enzyme, thereby enhancing the crop mechanical properties.

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Section: Water-soluble Cellulose Acetate and Other Artificial Donor-smentioning

confidence: 99%

“…Water-soluble cellulose acetate was synthesized by a modification of the method described by Gomez-Bujedo et al (2004). Cellulose acetate (1 g) was dissolved in 10 ml of acetic acid/methanol (2.8:1, v/v) with shaking for 16 h at 20°C.…”

Section: Preparation Of Wscamentioning

confidence: 99%

Mixed‐linkage β‐glucan : xyloglucan endotransglucosylase, a novel wall‐remodelling enzyme from Equisetum (horsetails) and charophytic algae

Fry¹,

Mohler²,

Nesselrode³

et al. 2008

The Plant Journal

106

135

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“…339,340 Cellulose that has been rendered water soluble by partial acetylation can be oxidized to partially acetylated polyglucuronic acids. 341 β-Cyclodextrin is partially oxidized under the normal bleach conditions. 283,342 If the secondary alcohol groups on cyclodextrin are protected, the material can be almost completely oxidized to the per(5-carboxy-5-dehydroxymethyl) derivative.…”

mentioning

confidence: 99%

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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The discovery in 1959 of stable nitroxide‐based free radicals such as the prototypical 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) led to their use as electron spin resonance (ESR) spin labels in chemistry, biomedicine, and materials science. These nitroxides are prepared by the oxidation of secondary amines that contain no hydrogen atoms on the alpha‐carbons. The unique redox properties of nitroxides enable their use as oxidants in organic synthesis. The varied preparation and uses of oxoammonium salts as stoichiometric oxidants for alcohols are one subject of this review. Oxoammonium ions as oxidants for alcohols have a number of advantages, for example, the method is heavy‐metal free and some of the reactions can be performed in water or aqueous mixtures. A few side reactions are associated with these oxidations. The most serious is the fast reaction of the oxoammonium ion with free amines The several ways these oxidation reactions can be carried out are discussed in detail. They are: Oxidations using stoichimetric quantities of preformed oxoammonium salts carried out in either acidic, neutral, or basic conditions; reactions in which stoichiometric quantities of oxoammonium salts are generated in situ by disproportionation of a nitroxide in the presence of a strong acid; nitroxide‐catalyzed oxidations using a secondary oxidant; efficient nitroxide‐catalyzed oxidations of primary alcohols to carboxylic acids; and oxidations of primary alcohols or hemiacetals that can lead to lactones.

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“…90 Water insoluble polysaccharides, such as cellulose, are only oxidized on the edges of the fibers. 91,92 Pretreated celluloses give more uniform oxidations.…”

Section: Oxidations Leading To Linear Carboxylic Acidsmentioning

confidence: 99%

Nitroxide‐Catalyzed Alcohol Oxidations in Organic Synthesis

Brückner

2010

Stable Radicals

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Preparation of Cellouronic Acids and Partially Acetylated Cellouronic Acids by TEMPO/NaClO Oxidation of Water-Soluble Cellulose Acetate

Cited by 72 publications

References 24 publications

Mixed‐linkage β‐glucan : xyloglucan endotransglucosylase, a novel wall‐remodelling enzyme from Equisetum (horsetails) and charophytic algae

Mixed‐linkage β‐glucan : xyloglucan endotransglucosylase, a novel wall‐remodelling enzyme from Equisetum (horsetails) and charophytic algae

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

Nitroxide‐Catalyzed Alcohol Oxidations in Organic Synthesis

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