P-glucosidases

Potential enzymes involved in anthocyanin metabolism — The lactase phlorizin hydrolase (LPH EC 3.2.1.108) present only in the small intestine on the outside of the brush border membrane and the cytosolic P-glucosidase (CBG EC 3.2.1.1) found in many tissues, particularly in liver, can catalyze the deglycosylation (or hydrolysis) of polyphenols. LPH may play a major role in polyphenol metabolism... 

Two main groups can be discerned (1) endogenous factors such as plant enzymes like polyphenoloxidase, peroxidase, and P-glucosidase and (2) conditions prevailing in the extraction medium will decide the fates of betalain pigments among which temperature, oxygen, and pH are considered the most important conditions. 

Different types of gel materials, such as polysaccharides, proteins and synthetic polymers, are now used to entrap biocatalysts. Among them, photo-crosslinkable resin prepolymer ENTP-4000 as shown in Eig. 7 is more useful compared to others. Entrapment of biocatalysts should be carried out under the illumination of near ultraviolet hght within 3-5 min, by which high temperatures, shifts of pH to extremely alkahne or acidic sides are avoided. ENTP-4000, hydrophobic photo-crosslinkable resin prepolymer, is one of the most suitable prepolymers for entrapment of p-glucosidase. Molecular weight of its main chain is about 4000. 

Protein isolation with affinity precipitation has been discussed in detail by Mattiasson and co-workers (see, e.g. Galaev and Mattiassion, 1997) and they have provided an exhaustive tabulation. Polymers varied from alginate.s/chitosan to dextran to NIPAM. Examples of the used proteins are from trypsin, p-glucosidase, xylanase, alkaline protease, etc. It is remarkable that affinity precipitation can sometimes give results comparable to affinity chromatography. 

The Shen group has devised a domino process wherein after an enzymatic cleavage of a glycoside a rearrangement sequence takes place [18]. Subjecting multifloroside 8-38 to P-glucosidase in acetate buffer (Scheme 8.10) afforded jasmolac-tone analogues such as 8-39 in a rather low yield. 

Some studies indicated that exogenous zearalenone influences plant growth and development. For example, zearalenone stimulated the initiation of the vegetative bud in tobacco pith callus tissue (Mirocha et al. 1968), inhibited the cell membrane transport of maize roots (Vianello and Macri 1981) and enhanced the a-amylase and P-glucosidase activities of germinating maize seeds. 

Thus, samarium(III)-triflate-promoted reactions provided O-linked disaccharides in moderate to excellent yields [308]. Szeja and Niemiec reported the use of 5-nitro-S-pirydyl glucoside as glycosyl donors in P-glucosidase-catalyzed glycosylation of alcohols [494]. 

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