[Suitability of naphthyl-alpha-L-fucosides for the investigation of alpha-L-fucosidases (author's transl)]

Abstract

In comparison with 1- and 2-naphthyl beta-D-glucoside, beta-D-galactoside, beta-D-glucuronide, beta-D-N-acetylglucosaminide, alpha-D-glucoside, alpha-D-galactoside and alpha-D-mannoside 1- and 2-naphthyl alpha-L-fucoside are hydrolyzed more quickly or to the same extent by homogenates prepared from freeze-dried cryostate sections of various rat organs. Nevertheless, when the fucosides are employed for the histochemical demonstration of alpha-L-fucosidase mostly negative data were obtained independent on the method used, whereas all other naphthyl glycosies deliver positive results. The reasons for these discrepancies are the marked inhibition of alpha-L-fucosidase by aldehyde fixation and diazonium salts. Then, alpha-L-fucosidase activity is suppressed to 90% and between 85 and 98% respectively; the inhibition of alpha- and beta-D-glucosidase, alpha- and beta-D-galactosidase, alpha-D-mannosidase, beta-D-glucuronidase and beta-D-N-acetylglucosaminidase by the fixative or coupling reagent does not exceed 70%. Therefore 1- and 2-naphthyl alpha-L-fucoside cannot be recommended in general for histochemical purposes. Small amounts of dimethylformamide do not influence the activity of most of the glycosidases investigated. For biochemical measurements, however, especially 1-naphthyl alpha-L-fucoside represents a suitable alternative in a fluorometric procedure instead of p-nitrophenyl alpha-L-fucoside used for the photometric evaluation of alpha-L-fucosidase. With the fluorometric method the enzyme was measured in rat organs, which posses remarkably different activities of alpha-L-fucosidase.