Melibiose preparation

Melibiosone was prepared by the action of benzaldehyde on melibiose phenylosazone17-191 and was identified by conversion into melibiose p-bro-mophenylosazone. On treatment with emulsin, it was hydrolyzed to D-glucosone and D-galactose.17,203... 

Melibiose. An octaacetylmeUbiononitrile of 64% purity was prepared by Zempl n in about 50% yield, from pure melibiose oxime. It was degraded in a 68-78% yield to 5-(a-D-galactopyranosyl)-D-arabinose, obtained only in solution. 

Melibiose Phenylhydrazone and Melibiose Phenylosazone. These were prepared by the method of Scheibler and Mittelmeier (60), mp 145 °C and 178 °C, respectively. 

Melibiose occurs in Nature primarily as a constituent of the trisaccharide raffinose, although it has been identified in such plant exudates as ash manna and an exudate from mallow. Historical details of the discovery and preparation of melibiose have been reviewed by Harding68 and will not be reiterated here. Modern methods for the preparation of melibiose have been recorded by Hudson and Harding60 and by Bates and associates.66 Melibiose can be purchased from a number of chemical-supply firms. 

Fletcher and Diehl, in studying the preparation of melibiose from raffinose by the fermentative hydrolysis of the trisaccharide, noticed a new form of the disaccharide. By observing the mutarotation of the new form, and by comparing the infrared spectra with that of an authentic... 

The longest known compound in this series is 1,6-anhydro-a-D-galactofuranose (261). It is relatively easily obtainable, and is usually prepared by pyrolysis of D-galactose116,294,295,792 it can also be obtained by pyrolysis of lactose, melibiose, and raffinose.196,291 An alternative route consists in the reaction of 0.2 M hydrochloric acid, or 0.1 M sulfuric acid, with D-galactose.114,115 The anhydride 261 was originally mistaken for l,3-anhydro-/3-D-galactopyranose, because of... 

The readily accessible peracetates of lactose, maltose, and melibiose are converted in good yields into the corresponding 1,2-trans glycobiosyl azide hepta-acetates more conveniently than by the previously published procedure for the preparation of hepta-(9-acetyl-p-cellobiosyl azide (59). Later this formation of hepta-(9-acetyl-p-lactosyl azide (60) was reported as a novel procedure, and the corresponding melibiosyl derivative was again described. Compound 59 can also be obtained from an orthoester precursor with trimethylsilyl azide as already described, but this route does not enjoy any particular preparative advantage. 

Alpha-D-galactosidase (a-Gal EC 3.2.1.22) can directly transfer galactosyl residues to the CD rings. For example, add a-Gal to the buffer solution containing melibiose and CDs (a-CD, fi-CD, and y-CD) and incubate at 40°C for 48 h. The reactant contains mixtures of Gal-CDs (Gal-a-CD, Gal-)0-CD and Gal-y-CD), melibiose hydrolyzate, melibiose and CDs. This section will discuss preparation and purification of a-Gal, production of Gal-CDs by a-Gal and Gal-CDs structure analysis. 

Preparation. The sugar may be prepared by charcoal-column fractionation of the partial acid hydrolysis products of guaran (4 ) and by the alkaline isomerization of melibiose ( S). 

Preparation. Hydrolysis of raffinose by invertase yields melibiose 80) and D-fructose. By the use of bakers yeast (top yeast), hydrolysis and simultaneous removal of the D-fructose by fermentation takes place. The sirup crystallizes directly or after purification through the octaacetate. 

Kochetkov s method for preparing glycosylamines from free sugars by reaction with aqueous ammonium carbonate (Vol.20, p.l06) has been optimized for use with cellobiose, maltose, lactose and melibiose on a gram scale, and applied to a di- and hepta-saccharide the conversion of the glycosylamines into A -glycopeptides is covered in Section l.S. 

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