Substrates, chromogenic, glycosides

A. Patel and A. C. Richardson, 3-Methoxy-4-(2 -nitrovinyl)-phenyl glycosides as potential chromogenic substrates for the assay of glycosidases, Carbohydr. Res., 146 (1986) 241-249. 

Enzymic hydrolysis (25-40°C) at the heterosidic bond of the chromogenic substrates was followed either continuously (via formation of 2 -chloro,4 -nitrophenol) at pH 5.5 (O.D. 405 nm) or discontinuously (4-methylumbel-liferone fluorescence at pH 10, emission at A > 435, excitation at A366 nm). Reaction rates were calculated from the linear increase of O.D. (em = 9000 M-1cm-1) or fluorescence (standardization with 4-methylumbelliferone) versus time. Alternatively, an HPLC method was used to follow the formation of chromophoric reaction products, phenols and glycosides (1). Concentrations were calculated from peak heights after appropriate standardization. 

Most of the early tests were based on the hydrolysis of the natural sphingolipid which had been labelled in the hydrophilic portion. Thus, the substrate and products could be easily separated by two-phase solvent partition or by precipitation of the product. In many cases artificial chromogenic or fluorogenic glycosides could be used instead of radiolabelled substrates. However, in these cases it is very important to demonstrate that the conditions and specificities of the enzynie reactions are such that the results can be extrapolated to the natural substrate (e.g. Peters et al., 1975). Thus, in the case of Niemann-Pick or Krabbe s diseases the unsubstituted... 

Syntheses and applications as chromogenic substrates of IV-acetyl- -D-hexosaminidase of 4-[(3,5-dichloro-4-hydrm henyl)amino]phenyl, indophenyl, and the water soluble 3,4-dinitropheityl 2-acetamido-2-deoxy-/ l-D-glucopyranosides have been reported. Metl I, allyl and bemyl l-amino-l-deoxy-a-D-fructofuranosides were thesized from 1-amino-1-deojy-D-fructose by Fischer glycosidation of the IV-protected derivatives (75)... 

Syntheses of amino-sugar glycosides and disaccharides, including chromogenic substrates for A -acetyl-p-D-glucosaminidase, are covered in Chapter 3. Synthesis of protected 2-amino-2-deoxy-glycosyl azides is covered in Chapter 10. 2,3,6-Trideoxy-5-0-(4-nitrobenzoyl)-3-trifluoroacetamido-L-riho-hexofuranosyl bromide, a furanoid ristosamine derivative, was synthesized from L-rhamnal via intermediates reported previously (Vol.25, p.253) to effect glycosylations. ... 

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