The hydrolysis of glycosyl fluorides by glycosidases

1. alpha-d- and beta-d-Glucopyranosyl, alpha-d- and beta-d-galactopyranosyl, alpha-d-mannopyranosyl and alpha-d-xylopyranosyl fluorides were hydrolysed specifically by the respective glycosidases from several sources. 2. Use of specific inhibitors with a mixture of glycosidases from Helix pomatia intestinal juice showed that each glycosyl fluoride was hydrolysed only by the respective glycosidase. alpha-d-Glucopyranosidase and alpha-d-xylopyranosidase activities were shown to be due to different enzymes. 3. Partially purified enzyme preparations containing only one of the glycosidase activities hydrolysed only the corresponding glycosyl fluoride. 4. The configuration at C-1 of alpha-d-mannopyranosyl fluoride was confirmed since it was hydrolysed by an alpha-d-mannosidase preparation that contained no detectable beta-d-mannosidase activity. 5. An attempt to prepare o-nitrophenyl beta-d-mannopyranoside led only to o-nitrophenyl alpha-d-mannopyranoside.

Fluorescein-labeled beta-glucosidase as a bacterial stain

Fluorescein isothiocyanate-labeled beta-glucosidase was used as a simple staining reagent with selected gram-positive and gram-negative organisms. Staining in situ appeared to be dependent on the presence of accessible glycosidic-type linkages in the bacterial cell wall. Extensive wall damage or lysis did not occur when stained cells were suspended in washing and mounting solutions. The apparent specificity of labeled enzyme for wall substance was tested by blocking reactions, staining of isolated cell walls, and failure to stain substances lacking appropriate glycosidic linkages. Severe cell wall lesions were produced after prolonged contact with labeled enzyme, and this phenomenon may also be related to staining specificity. Gram-negative organisms and spores were poorly stained unless protected glycopeptide substrate was previously exposed by treatment of cells with thioglycolic acid or dilute alkaline sodium hypochlorite solution. A potential for staining tissues and cell lines may also exist. Some possible applications of labeled enzymes are briefly discussed.

The enzymic hydrolysis of amygdalin

Chromatographic examination has shown that the enzymic hydrolysis of amygdalin by an almond beta-glucosidase preparation proceeds consecutively: amygdalin was hydrolysed to prunasin and glucose; prunasin to mandelonitrile and glucose; mandelonitrile to benzaldehyde and hydrocyanic acid. Gentiobiose was not formed during the enzymic hydrolysis. The kinetics of the production of mandelonitrile and hydrocyanic acid from amygdalin by the action of the beta-glucosidase preparation favour the probability that three different enzymes are involved, each specific for one hydrolytic stage, namely, amygdalin lyase, prunasin lyase and hydroxynitrile lyase. Cellulose acetate electrophoresis of the enzyme preparation showed that it contained a number of enzymically active components.