• Journal of Microbiology and Biotechnology
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• v.17 no.11
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• pp.1789-1796
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• 2007

A ${\beta}$-glucosidase with the molecular mass of 160,000 Da was purified to homogeneity from cell extract of a cellulolytic bacterium, Cellulomonas uda CS1-1. The kinetic parameters ($K_m$ and $V_{max}$) of the enzyme were determined with pNP-cellooligosccharides (DP 1-5) and cellobiose. The molecular orbital theoretical studies on the cellulolytic reactivity between the pNP-cellooligosaccharides as substrate (S) molecules and the purified ${\beta}$-glucosidase (E) were conducted by applying the frontier molecular orbital (FMO) interaction theory. The results of the FMO interaction between E and S molecules verified that the first stage of the reaction was induced by exocyclic cleavage, which occurred in an electrophilic reaction based on a strong charge-controlled reaction between the highest occupied molecular orbital (HOMO) energy of the S molecule and the lowest occupied molecular orbital (LUMO) energy of the hydronium ion ($H_3O^+$), more than endocyclic cleavage, whereas a nucleophilic substitution reaction was induced by an orbital-controlled reaction between the LUMO energy of the oxonium ion ($SH^+$) protonated to the S molecule and the HOMO energy of the $H_2O_2$ molecule. A hypothetic reaction route was proposed with the experimental results in which the enzymatic acid-catalyst hydrolysis reaction of E and S molecules would be progressed via $SN_1$ and $SN_2$ reactions. In addition, the quantitative structure-activity relationships (QSARs) between these kinetic parameters showed that $K_m$ has a significant correlation with hydrophobicity (logP), and specific activity has with dipole moment, respectively.

• Journal of Microbiology and Biotechnology
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• v.20 no.9
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• pp.1351-1358
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• 2010

The demand for ${\beta}$-glucosidases insensitive to product inhibition is increasing in modern biotechnology, for these enzymes would improve the process of saccharification of lignocellulosic materials. In this study, a ${\beta}$-glucosidase gene that encodes a 442-amino-acid protein was isolated from a marine microbial metagenomic library by functional screening and named as bgl1A. The protein was identified to be a member of the glycoside hydrolases 1 family, and was recombinantly expressed, purified, and biochemically characterized. The recombinant ${\beta}$-glucosidase, Bgl1A, exhibited a high level of stability in the presence of various cations and high concentrations of NaCl. Interestingly, it was activated by glucose at concentrations lower than 400 mM. With glucose further increasing, the enzyme activity of Bgl1A was gradually inhibited, but remained 50% of the original value in even as high as 1,000 mM glucose. These findings indicate that Bgl1A might be a potent candidate for industrial applications.

• The Korean Journal of Zoology
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• v.34 no.2
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• pp.159-172
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• 1991

It has been investigated what could be the selective marker distinguishing the immature from mature spermatozoa and whether fi -glucuronidase and fi -glucosidase are dependent on androgen in the luminal fluid of the epididymis or not. The contents of hexose, hexosamine and sialic acid in the epithelial cells, luminal fluid and spermatozoa of the epididymis were examined and the patterns of protein bands were compared in each group of the luminal fluid by SDS-PAGE. Lactate dehydrogenase, glucose-6-phosphatase, Na+ -K+ -ATPase and MgNa-ATPase showed higher activities in the cauda than the caput epididymal spermatozoa but only $Mg^2$+-ATPase activity appeared to be changed significantly. When the contents of hexose, hexosamine and sialic acid were analyzed and compared quantitatively, those of hexose were significantly different in the luminal fluid of caput and cauda epididymis, those of hexosamine in the epithelial cells and those of sialic acid in the epithelial cells and luminal fluid. When SDS-PAGE has been performed in each group, the band of MW 33-37 KD which was absent in the luminal fluid of caput epididymis appeared obviously in the luminal fluid of cauda epididymis and ako apeared in the cauda sperm crude membrane fraction. In addition, $\beta$ -glucuronidase and $\beta$ -glucosidase activities and their dependence on androgen were measured and the SDS-PAGE patiems of proteins and/or glycoproteins in the luminal fluid were examined. The activities of these two enzymes in the luminal fluid of the epididymis decreased significantly from the 5th day after castration. When testosterone was injected, the activity of $\beta$ -glucuronidase began to increase significantly from the 5th day following injection and that of $\beta$ -glucosidase from the loth day. On the other hand, the band of about MW 21 KD was newly observed in the lumen of caput epididymis when testosterone was administered.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.347-353
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• 2014

${\beta}$-Glucosidase from Aspergillus usamii KCTC 6954 was used to convert ginsenoside Rb1 to compound K, which has a high bio-functional activity. The enzymatic activities during culturing for 15 days were determined using ${\rho}$-nitrophenyl-${\beta}$-glucopyranoside. The growth rate of the strain and the enzymatic activity were maximized after 6 days (IU; $175.93{\mu}M\;ml^{-1}\;min^{-1}$). The activities were maximized at $60^{\circ}C$ in pH 6.0. During culturing, Rb1 was converted to Rd after 9 d and then finally converted to compound K at 15 d. In the enzymatic reaction, Rb1 was converted to the ginsenoside Rd within 1 h of reaction time and compound K could be detected after 8 h. As a result, this study demonstrates that $Rb1{\rightarrow}Rd{\rightarrow}F2{\rightarrow}$compound K is the main metabolic pathway catalyzed by ${\beta}$-glucosidase and that ${\beta}$-glucosidase is a feasible option for the development of specific bioconversion processes to obtain minor ginsenosides such as Rd and compound K.

• Journal of Food Hygiene and Safety
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• v.13 no.1
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• pp.20-23
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• 1998

The objective of this study was to evaluate the bifidogenic effect and a-glucosidase inhibitory effect of artificially cultured Phellinus linteus. The water extract of P. linteus promoted the growth of Bifidobacterium breve as well as the decrease of final pH in the media culturing intestinal bacteria. The growth of lactic acid bacteria inhibited effectively the bacterial enzymes, ${\beta}-glucosidase,\;{\beta}-glucuronidase$ and tryptophanase, of intestinal bactetria. The water extract of P. linteus inhibited maltase, sucrase and ${\alpha}-amylase$ of rat intestine.

• Journal of Microbiology and Biotechnology
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• v.17 no.5
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• pp.745-752
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• 2007

A $\beta$-glucosidase from the algal lytic bacterium Sinorhizobium kostiense AFK-13, grown in complex media containing cellobiose, was purified to homogeneity by successive ammonium sulfate precipitation, and anion-exchange and gel-filtration chromatographies. The enzyme was shown to be a monomeric protein with an apparent molecular mass of 52 kDa and isoelectric point of approximately 5.4. It was optimally active at pH 6.0 and $40^{\circ}C$ and possessed a specific activity of 260.4 U/mg of protein against $4-nitrophenyl-\beta-D-glucopyranoside$(pNPG). A temperature-stability analysis demonstrated that the enzyme was unstable at $50^{\circ}C$ and above. The enzyme did not require divalent cations for activity, and its activity was significantly suppressed by $Hg^{+2}\;and\;Ag^+$, whereas sodium dodecyl sulfate(SDS) and Triton X-100 moderately inhibited the enzyme to under 70% of its initial activity. In an algal lytic activity analysis, the growth of cyanobacteria, such as Anabaena flos-aquae, A. cylindrica, A. macrospora, Oscillatoria sancta, and Microcystis aeruginosa, was strongly inhibited by a treatment of 20 ppm/disc or 30 ppm/disc concentration of the enzyme.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.901-907
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• 2008

Thermotoga neapolitana $\beta$-glucosidase (BglA) was subjected to site-directed mutagenesis in an effort to increase its ability to synthesize arbutin derivatives by transglycosylation. The transglycosylation reaction of the wild-type enzyme displays major ${\beta}(1,6)$ and minor ${\beta}(1,3)$ or ${\beta}(1,4)$ regioselectivity. The three mutants, N291T, F412S, and N291T/F412S, increased the ratio of transglycosylation/hydrolysis compared with the wild-type enzyme when pNPG and arbutin were used as a substrate and an acceptor, respectively. N291T and N219T/F412S had transglycosylation/hydrolysis ratios about 3- and 8-fold higher, respectively, than that of the wild-type enzyme. This is due to the decreased hydrolytic activity of the mutant rather than increased transglycosylation activity. Interestingly, N291T showed altered regioselectivity, as well as increased transglycosylation products. TLC analysis of the transglycosylation products indicated that N291T retained its ${\beta}(1,3)$ regioselectivity, but lost its ${\beta}(1,4)$ and ${\beta}(1,6)$ regioselectivity. The altered regioselectivity of N291T using two other acceptors, esculin and salicin, was also confirmed by TLC. The major transglycosylation products of the wild type and N291T mutant were clearly different. This result suggests that Asn-291 is highly involved in the catalytic mechanism by controlling the transglycosylation reaction.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1986.12a
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• pp.525.1-525
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• 1986

To clone ${\beta}$-glucosidase gene from Cellulomonas sp. a gene library was constructed using E. coli JM83 pUC9. Among 2,500 pseudotransformants obtained, 20 clones developed yellow color on the p-nitrophenyl- -D-glucopyranoside filter paper These 20 clones were classified into three groups based on the results of activity staining using nondenaturating polyacrylamide gel electrophoresis and restriction enzyme digestions. Among the three groups, only one group containing pCEl plasmid has specificity for cellobiose.

• Proceedings of the Korean Society of Crop Science Conference
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• 2006.04a
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• pp.594-595
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• 2006

• Food Science of Animal Resources
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• v.37 no.5
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• pp.735-742
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• 2017

This study was conducted to isolate and characterize Paenibacillus sp. MBT213 possessing ${\beta}$-glucosidase activity from raw milk, and examine the enzymatic capacity on the hydrolysis of a major ginsenoside ($Rb_1$). Strain MBT213 was found to have a high hydrolytic ability on ginsenoside $Rb_1$ by Esculin Iron Agar test. 16S rDNA analysis revealed that MBT213 was Paenibacillu sp. Crude enzyme of MBT213 strain exhibited high conversion capacity on ginsenoside $Rb_1$ into ginsenoside Rd proven by TLC and HPLC analyses. The API ZYM kit confirmed that Paenibacillu sp. MBT213 exerted higher ${\beta}$-glucosidase and ${\beta}$-galactosidase activity than other strains. Optimum pH and temperature for crude enzyme were found at 7.0 and $35^{\circ}C$ in hydrolysis of ginsenoside $Rb_1$. After 10 d of optimal reaction conditions for the crude enzyme, ginsenoside $Rb_1$ fully converted to ginsenoside Rd. Ginseng roots (20%) were fermented for 14 d, and analyzed by HPLC showed that amount of ginsenoside $Rb_1$ significantly decreased, while that of ginsenoside Rd was significantly increased. The study confirmed that the ${\beta}$-glucosidase produced by Paenibacillus sp. MBT213 can hydrolyze the major ginsenoside $Rb_1$ and convert to Rd during fermentation of the ginseng. The ${\beta}$-glucosidase activity of this novel Paenibacillus sp. MBT213 strain may be utilized in development of variety of health foods, dairy foods and pharmaceutical products.