Almond 3-D-glucosidase

The synthesis of b -hydroxyhexyl P-D-glucopyranoside using almond (3-d-glucosidase (Figure 12.5). 

Appreciable use continues to be made of enzymes in the synthesis of glycosides. The use of almond /3-D-glucosidase in 90% acetonitrile, which gives /3-glucosides, can be employed at the concentration of 5g per litre. In a further example a lactase has been employed to synthesis the gypsy moth antifeedant substance 29 by use of 2-nitrophenyl p-o-glucopyranoside as donor. 

Immobilization of (3-D-glucosidase from almonds on photo-crosslinkable resin prepolymer (ENTP-4000) was carried out by the following procedure. One gram of ENTP-4000 was mixed with 10 mg of a photosensitizer, benzoin ethyl ether, and 110 mg of (3-D-glucosidase from almonds (3.4 units mg ). The mixture was layered on a sheet of transparent polyester film (thickness, ca. 0.5 mm). The layer was covered with transparent thin film and then illuminated with chemical lamps (wavelength range 300 00 nm) for 3 min. The gel film thus obtained was cut into small pieces (0.5 x 5 x 5 mm) and used for bioconversion reaction. 

Results are expressed as fig of p-nitrophenol liberated per g of seed from 6 mM p-nitrophenyl a-D-mannoside in 1 hr at 37° and pH 5. Coarsely ground beans. Defatted sweet-almond meal. A commercial /3-D-glucosidase preparation purified from emulsin. a-D-Mannosidase activity is given per g of purified material. 

The l,2,6-trideoxy-l,6-imino-D-ara6m<9-hexitol was found to inhibita-D-glucosidase (Ki 12 pM, Bakers yeast), (3-D-glucosidase (Ki 51 pM, Almonds) and (3-D-galactosidase (Ki 13 pM, E. coli) as well, indicating the flexibility of the 7-membered ring system (14). 

D-glucosidase of almond emulsin is without action on melezitose or turanose - Next there is the positive evidence that the enzyme a-D-glucosidase which is obtainable from yeast, malt, Aspergillus oryzae and some other organisms, hydrolyzes both turanose and melezitose, the latter to its three components. The action of enzymes thus discloses that both D-glucose units in melezitose are of the a-n-type, and melezitose becomes 3-[ a-o-glucopyrano3ylJ-D-fructofuranose < > a-n-glu-copyranose. 

An enzymic differentiation between the three trehaloses comes from the observation that almond emulsin (/3-D-glucosidase) acts on /3, 8-trehalose much more quickly than on the a,a- or a,/8-isomers, and Peat, Whelan, and Hinson have synthesized /3, 8-trehalose from D-glucose, using ahnond emulsin. 

Glucosidase, prepared from sweet or bitter almonds, acts both on ordinary /3-D-glucosides (heterosides) (I) and on disaccharides (holosides),... 

The effect on /3-glucosidase activity of substitution in the glucon has been carefully investigated by the school of Helferich. It has been established that substitution of the hydroxyl groups at C2, C3 and C4 renders the /3-D-glucopyranoside unhydrolyzable (i.e., E.V. less than 10 s) by almond emulsin. This refers to phenyl 3-methyl-/3-D-gluco-pyranoside,29 phenyl 2,4,6-trimethyl-/3-D-glucopyranoside89 and to the... 

The first evidence for the presence of an a-D-mannosyl link in ovalbumin glycopeptides was provided by the action of almond emulsin,101,102 although the absence of /3-D-mannosidase from the enzyme preparation was not confirmed until later.103 The presence of 2-acetamido-2-deoxy-/M>glucosidase in emulsin left doubt as to the terminal position of all of the D-mannose released. 

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