Cellobiose transfer from

Linear Homotrisaccharides. - The nephritogenoside trisaccharide unit a-D-Glc-(1- 6)-P-d-G1c-(1- 6)-a-D-Glc has been prepared by application of the glycosyl sulfoxide procedure. Cellotriose can be made from cellobiose by use of a sesame seed transferase which also transfers from other disaccharide substrates. Treatment of highly concentrated aqueous solutions of D-mannose with an a-mannosidase from Aspergillus niger has resulted in the isolation of the trimers a-D-Man-(l- 2)-a-D-Man-(l->6)-D-Man and a-D-Man-(l 2)-a-D-Man-(1 ->2)-D-Man, and this latter trisaccharide has been formally synthesized by Fraser-Reid and colleagues in studies of the mannan components of phosphatidylinositol membrane anchors. In the course of the work they used the orthoesters 4 as versatile synthetic intermediates. ... 

Crook and Stone reported the formation of a series of oligosaccharides by /J-glucosyl transfer from cellobiose in the presence of enz5unes from several sources. Tlffee disaccharides and two trisaccharides were isolated after column chromatography on activated charcoal of the digest of cellobiose by a partially piuified enzyme from A. niger. 

A collection of redox enzymes for which efficient DET with electrodes has been observed is given in Table 2.3. Most of them are metaUoenzymes containing iron or copper. Many of these enzymes are part of electron transfer chains, i.e., have macromolecular redox partners, or react on large substrates. The evidence for DET has not always been presented by direct electrochemical measurements. In many cases the DET has been proved indirectly by measurement of a substrate dependent catalytic current. Various metabolites ranging from sugars such as fructose, cellobiose and gluconate [6], amines like methylamine and histamine [123], lactate [91],p-cresol [93] and drugs such as benzphetamine [74] can be measured with enzymes in direct contact to an electrode. The bioelectrocatalytic reaction of peroxide is one of the most important reactions not only for the determination of peroxide(s) in various media but also substrates of coupled oxidase [8] and enzyme inhibitors [130, 252]. Furthermore, enzyme immunoassays have been developed based on DET of peroxidase and laccase and electrodes [7,131,132]. 

Direct electron transfer-a favorite electron route for cellobiose dehydrogenase (CDH) from Trametes villosa. Comparison with CDH from Phanerochaete chrysosporium. Langmuir, 22 (25), 10801-10806. 

An insoluble, enzyme preparation (sedimenting at 100,000 g) has been obtained by Glaser it is capable of catalyzing the transfer of D-gluco-pyranosyl residues from uridine 5-(a-D-glucopyranosyl-C pyrophosphate) to form a radioactive, water-insoluble, alkali-insoluble polysaccharide. This product was identified as cellulose by (a) hydrolysis with the cellulase of Myrotkecium verrucaria, and (b) identification, as cellobiose, of the radioactive disaccharide obtained by acid hydrolysis—by repeated recrystallization with authentic cellobiose without loss of specific activity. 

Bipyridine (bpy) diboronic acid 239 developed by Nakashima and its iron (II) (as FeC12) complex produce CD-active saccharide complexes. The CD activity of 239 was derived from the asymmetric immobilization of the two-pyridine units on saccharide binding. The copper(II) complex gave a CD band in the region of the metal to ligand charge transfer band. A or A complexes were found depending on the complexed saccharide. For example, the o-maltose complex adopted A chirality whereas the o-cellobiose complex adopted A chirality. 

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