D-glucose and L-arabinose

Neutral solutions of pure aldoses exhibit no selective absorption in the ultraviolet region103 106 such an absorption may, however, be observed108 for solutions of D-glucose and L-arabinose in 50% sulfuric acid, and is... 

A glycoalkaloid, nervosine, C36H53O12N, was isolated as its picrate (mp 131° [a] -I-12.8° as hydrochloride). Alkaline hydrolysis generated lindelofidine (d-isoretronecanol) and an acid which on hydrolysis with acid generated D-glucose and L-arabinose. The disaccharide obtained on mild hydrolysis was reduced with sodium borohydride and then hydrolyzed further. There was obtained arabinose, indicating that the aldehyde function of the glucose is coupled with the phenolic hydroxyl of the acid moiety. Exhaustive spectral analysis of the latter as well as of its tetrahydro derivative show that nervosine is LXXXIV 132). 

D-Glucose and L-arabinose have been converted into l,3-diamino-l,3-dideoi -D-direitol and D-erythritol respectively as potential glycosidase inhibitors. The same paper also describes the preparation of unusual urea and thiourea derivatives such as 21 and 22 also as potential glycosidase inhibitors. 

Fig. 3.—Relationship between D-glucose and D-xylose, D-galactose and L-arabinose.

In addition there is other evidence pointing to the fact that the same enzyme is involved in reactions with both D-fructose and L-arabinose. First, the relative rates of reaction with D-fructose and L-arabinose, respectively, remain constant after partial inactivation of the enzyme by heat. Second, the enzyme catalyzing both reactions is produced to a marked extent when sucrose is used as substrate for the growth of the organisms, but not when D-glucose or L-arabinose is used sucrose phos-phorylase is an adaptive enzyme. Third, on fractionation of the enzyme preparation with various concentrations of ammonium sulfate, the relative activities of the fractions are the same for both sugars. These observations indicate not only that the same enzyme is involved in both reactions but also that no additional enzyme is required for the formation of D-glucosyl-L-arabinose. 

D-Xylose was found to yield 2-furaldehyde almost exclusively, but D-lyxose, D-ribose, and L-arabinose produce another, as yet unidentified, compound absorbing at 289 nm, which is the maximum absorption wavelength for reductic acid. D-Glucose, D-fructose, and sucrose give almost identical yields (—85%) of 5-(hydroxymethyl)-2-fural-dehyde, but D-galactose and D-mannose give much lower yields thereof. 

The reaction was also studied with acetylated and benzoylated pyranose and furanose derivatives of D-galactose,18 D-mannose,19 D-lyxose,20 L-rhamnose,10 D-ribose, D-xylose, and L-arabinose,21 and with some partially benzoylated D-glucoses.22... 

Despite the broad spectrum of distribution, the catalytic properties of the enzyme in the different species are remarkably similar. The same four sugars (D-glucose, D-galactose, D-xylose, and L-arabinose) are substrates for the enzyme from all sources (Table VI). Some changes, however, have taken place, and the marginal activity for maltose found in the lower species (67) has been lost in the mammals, whereas the relative activity towards the pentoses has become enhanced. The Km values and turnover numbers for the substrates of purified beef kidney mutarotase are given in Table V. 

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