Plant cell-walls preparation

A further problem is that many of the methods for plant cell-wall preparation, based upon insolubility in aqueous buffers, salt solutions, and organic solvents, undoubtedly remove, or detach, some of the molecules, present in the intact wall, which may have important, structural functions. 

Harris, P.J., Blakeney, A.B., Henry, R.J., and Stone, B.A. 1988. Gas chromatographic determination of the monosaccharide composition of plant cell wall preparations. J. Assoc. Off. Anal. Chem. 71 272-275. 

GLC procedures are widely used for methyl ester determinations after saponification with 0.5N base, methanol is measured by GLC on columns of Poropak Q at 120°C (W), or on Carbowax 1500 at 125°C ( ). In the latter study, analyses were conducted on small samples of isolated plant cell wall preparations. In studies on the enzymatic incorporation of methyl groups from... 

This study is the first report of the presence of rhamnogalacturonan n in fruit-derived products with the exception of the RG-n from wine [20]. Our RG-II preparations correspond very closely to the described model [1,13], confirming the conservation of its structure among plant cell walls. The complexity of the structure and composition of RG-II with several rare sugars uneasy to identify may be one possible explanation of why this fascinating molecule remained undetected in apple juices for such a long time. 

Many different glycosyltransferase activities involved in higher plant wall biosynthesis have been identified in cell free membrane fractions, but in only a few cases has glycosyltransferase activity been retained in detergent-solubilized preparations, and in even fewer cases have any purified polypeptides been identified as plant cell wall glycosyltransferases (29,33). 

The xylanolytic enzyme system of T. reesei consists of several endoxy-lanases, at least three different exoglycosidases and at least two acetyl esterases. These enzymes contribute to the hydrolysis of plant cell walls in many of the applications of cellulolytic T. reesei enzyme preparations. A schematic figure of the suggested hydrolysis mechanism of xylans by the... 

Many experiments have demonstrated the capacity of cellulases and of mixtures of cellulases, pectinases, and hemicellulases to break down or to soften plant cell walls. For human diets this would be beneficial in preparing infant or geriatric foods where reduced fiber content is desired. Recently treatment of wheat bran was found to increase the in vitro protein digestibility by 35% (63) and to increase weight gain of rats fed a bran-containing ration. The aleurone cell wall was the primary substrate for these enzymes. 

Xylan, a xylose polymer having a pi,4-glycosidic linkage in the main chain, is the important component of hemicellulose in plant cell walls. Kobayashi et al. (121) reported that synthetic xylan that consists exclusively of xylose units can be prepared by the crude cellulase (containing xylanase) polymerization of P-xylobiosyl fluoride as a monomer in a mixed solvent of acetonitrile/acetate buffer. The reaction proceeded to produce Pl,4-linked synthetic xylan with a degree of polymerization of 23. 

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