8-Glucosidases properties

Emil Fischer developed a strong interest in the structural requirements for enzyme activity as the result of effects of changes in the structures of the a-and -methyl glucosides on their properties as substrates for the enzymes invertin and emulsin, which, as we have seen, he had shown to be a- and yS-glucosidases, respectively. As already mentioned, he was fascinated in 1895 by the fact that emulsin had no effect on either the a- or /2-methyl xylosides (33). In a 1912 publication with Karl Zach (34), he reported that -methyl 6-deoxyglucoside was hydrolyzed by emulsin and wrote ... 

This paper will review our studies on 1) B-amylase of C. thermosulfUrogenes 2) a-glucosidase of C. thermohydrosulfuricum 3) glucose isomerase of C. thermosulfurogenes and Thermoanaerohacter strain B6A and, 4) endoxylanase of Thermoanaerohacter strain B6A. A separate paper by Saha et al., in this symposium, will report on the properties of the novel pullulanase present in these thermoanaerobes. 

During the past year, several new studies have been published on -D-glucosidase IME systems that attempt to fulfill these process-relevant criteria. Immobilization of -D-glucosidase by attachment to polyurethane foam (40) has shown some promise as an economical IME system due to the support s resistance to enzymatic and microbial degradation, advantageous physical properties, and improved kinetics. However, the potential for fouling by particulate matter exhibited by foams renders these supports... 

Table I. Comparison of the Physicochemical Properties of Free (Novozym SP188) and Macrosorb KAX Immobilized -D-glucosidase...

Tabopda TK, Ngoupayo J, Awoussong PK, Mitaine-Offer AC, Ali MS, Ngadjui BT, Lacaille-Dubois MA. (2008) Triprenylated flavonoids from Dorstenia psilurus and their a-glucosidase inhibition properties. J Nat Prod 71 2068-2072. 

G. Legler, Action mechanism of glucosidase-splitting enzymes. II. Isolation and enzymatic properties of two 3-glucosidases from Aspergillus wentii, Hoppe Seyler s Zeitschr. Physiol. Chem., 348 (1967) 1359-1366. 

K. Osiecki-Newman, D. Fabbro, G. Legler, R. J. Desnick, and G. A. Grabowski, Human acid P-glucosidase Use of inhibitors, alternative substrates and amphiphiles to investigate the properties of the normal and Gaucher disease active sites, Biochim. Biophys. Acta, 915 (1987) 87-100. 

Another method which may become a useful technique for selective inactivation of cellulases in enzyme mixtures is the use of selective heat inactivation. While establishing the thermostability properties of crude xylanases from a fungal strain Y-94, Mitsuishi et al. (80) observed differential heat labilities of the cellulase and xylanase activities in the culture filtrate. After an incubation period of 20 minutes at 65°C, the xylanase activity was reduced by 5-10% whereas the Avicelase and /3-glucosidase activities were reduced by 100% and 60%, respectively. We have observed a similar temperature dependency of xylanase and cellulase activities in T. auranti-acus. As indicated in Figure 2, treatment of the culture filtrate at 70°C for 20 minutes resulted in less than a 5% loss in xylanase activity whereas cellulase activities were reduced by 40-50%. A similar effect has also been observed for the xylanases and cellulase enzymes produced in culture filtrates from T. harzianum (93). Further work in the area of heat treatments may improve the effectiveness of cellulase inactivation. Since the cellulase activities of some enzyme preparations can be more rapidly inactivated on... 

Robinson, D Price, R. G. and Dance, N. (1967). Separation and properties of beta-galactosidase, beta-glucosidase, beta-glucuronidase and A-acetyl-beta-glucosaminidase from rat kidney. Biochemical Journal 102 525. 

In support of his belief that cellobiohydrolase cannot be identified with Ci, Reese also argues that the hydrolytic property (cellobiohydrolase) normally manifested by Ci is of relatively low concentration (18) which is true. Figure 7 shows the fractionation of P. funiculosum on DEAE-Sephadex into Cu Cx, and / -glucosidase activities (13) it also shows the fact that the specific activity of the Cx component (peak 2) in terms of its activity on H3PC>4-swollen cellulose is very low in comparison... 

Shobana, S., Sreerama, Y. N., and Malleshi, N. G. (2009). Composition and enzyme inhibitory properties of finger millet (Eleusine coracana L.) seed coat phenolics Mode of inhibition of a-glucosidase and pancreatic amylase. Food Chem. 115,1268-1273. 

The palatability of safflower meal to poultry tends to be low (Ravindran and Blair, 1992) due to the presence of two phenolic glucosides matairesinol-p-glucoside, which imparts a bitter flavour, and 2-hydroxyarctiin-p-glucoside, which also has a bitter flavour and has cathartic properties (Darroch, 1990). Both glucosides are associated with the protein fraction of the meal, and they can be removed by extraction with water or methanol, or by the addition of P-glucosidase. 

Properties of a Recombinant (3-Glucosidase from Polycentric Anaerobic Fungus Orpinomyces PC-2 and Its Application for Cellulose Hydrolysis... 

In this article, we report the cloning in Escherichia coli and sequencing of an Orpinomyces P-glucosidase cDNA. The enzyme was overexpressed in and secreted from the yeast Saccharomyces cerevisiae. Physiochemical properties of the secreted enzyme were determined after it was purified. Its applicability for cellulose saccharification was also assessed. 

Crombie, H.J., Chengappa, S., Hellyer, A. and Reid, J.S.G. (1998). A xyloglucan oligosaccharide-active, transglycosylating beta-D-glucosidase from the cotyledons of nasturtium (Tropaeolum majus L) seedlings — purification, properties and characterization of a cDNA clone. Plant J., 15, 27-38. 

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