P-D-Xylosidase

Heterologous Expression of Aspergillus niger P-D-Xylosidase (XInD) Characterization on Lignocellulosic Substrates... 

P-D-Xylosidase from Seienomonas ruminantium Catalyzed Reactions with Natural and Artificial Substrates... 

The extents of sialylation of eleven plasma hydrolases have been examined. Most plasma hydrolases e.g. a-L-fucosidase and a-D-mannosidase) were eluted from DEAE-cellulose at a lower salt concentration after treatment with neuraminidase, although the elution profiles of p-D-glucosidase, P-D-xylosidase, and acid phosphatases were unaffected, indicating that they are less susceptible to the action of neuraminidase. The structure (9) assigned (G. Spick, B. Bayard, B. Fournet, and G. Strecker, F.E.B.S. Letters, 1975, 50, 296) to the carbohydrate component of human serotransferrin has been confirmed by high-resolution H n.m.r. spectroscopy. Electrophoresis separated human serotransferrin into four molecular forms that contain different proportions of bound iron. The nature of the interaction of renins from human and rabbit kidneys with immobilized concanavalin A, and their subsequent desorption with methyl a-D-mannopyrano-side, suggested that both proteins are glycosylated. ... 

Xylan endo-l,3-P-D-xylosidase Streptomyces sp., Aspergillus niger, Sporotrichum dimorphosporum 8, 10, 13 ... 

D-Xylosidase (EC 3.2.1.37), acetylesterase (EC 3.1.1.6), and a-L-arabinofuranosidase (EC 3.2.1.55) activities were determined using the synthetic substrates 1 mM p-nitrophenyl- 3-D-xylopyranoside, 5 mM p-nitrophenyl-acetate, and 5 mM p-nitrophenyl-a-L-arabinofuranoside (all from Sigma). Release of p-nitrophenol was monitored spectrophoto-metrically at 410 nm using a Jasco V-530 Spectrophotometer. 

P-Xylosidases are being used commonly in paper industry for complete degradation of xylans. The enzymes used in the synthesis of xylose-containing compounds have also been reported. For example, Eneyskaya et al. (50) have used />-nitrophenyl P-D-xylopyranosides (XyiPpNP) as a donor and a 3-xylosidase ixom Aspergillus sp. in the synthesis of several 31,4-D-xylooli-gosaccharides as P-xylanase substrates. 

T. Kasumi, Y. Tsumuraya, C. F. Brewer, H. Kersters-Hilderson, M. Claeyssens, and E. S. Hehre, Catalytic versatility of Bacillus pumilus P-xylosidase Glycosyl transfer and hydrolysis promoted with a- and P-D-xylosyl fluoride. Biochemistry 26 3010 (1987). 

Fig. 6. The action of glycosidases on XXFG. a-L-Fucosidase (F) can attack at any time [37], whereas a-o-xylosidase (X) and P-D-glucosidase (G) must act in the sequence shown [35]. Other abbreviations...

P-Glucosidase, p-xylosidase, and a-arabinofiiranosidase activities were determined by following the release of 4-nitrophenol from 4-nitrophenyl-P-D-glucopyranoside, 4-nitrophenyl-P-D-xylopyranoside, and 4-nitrophenyl-a-L-arabinopyranoside (Sigma), respectively, for 15 min at 50 °C and pH 4.0 (50 mM Na acetate buffer). The reaction was stopped by the addition of 1 M Na2C03, and the absorbance was read at 410 nm from a 4-nilrophenol standard curve. One unit of activity was defined as the amount of enzyme that released 1 pmol of 4-nitrophenol per min. 

The common identity of human acid jS-D-glucosidase and /3-D-xylosidase has been recognized (see p. 429). 

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