• Food Science and Preservation
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• v.3 no.1
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• pp.93-104
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• 1996

The cell wall components of fruit include cellulose. hemicellulose, pectin, glycoprotein etc., and the cell wall composition differs according to the kind of fruit. Fruit softening occurs as a result of a change in the cell wall polysaccharides : the middle lamella which links primary cell walls is composed of pectin. and primary cell walls are decomposed by a solution of middle lamella caused due to a result of pectin degradation by pectin degrading enzymes during ripening and softening, During fruit ripening and softening, contents of arabinose and galactose among non-cellulosic neutral sugars are notably decreased, and this occurs as a result of the degradation of pectin during fruit repening and softening since they are side-chained with pectin in the form of arabinogalactan and galactan Enzymes involved in the degradation of the cell wall include polygalacturonase, cellulose, pectinmethylesterase, glycosidase, etc., and various studies have been done on the change in enzyme activities during the ripening and softning of fruit. Among cell wall-degrading enzymes, polygalacturonase has the greatest effect on fruit softening, and its activity Increases during the maturating and softening of fruit. This softening leads to the textural change of fruit as a result of the degradation of cell wall polysaccharides by a cell wall degrading enzyme which exists in fruit.

• Journal of Applied Biological Chemistry
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• v.43 no.3
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• pp.141-146
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• 2000

Glycosidase activities were tested from the grape berries, Vitis labruscana B. Takasumi. Among various glycosidases, $\alpha$-D-galactosidase was found to be the most active in the flesh and other glycosidases were considerably active in the order of the following: $\alpha$-D-mannosidase>$\alpha$-D-glucosidase>$\beta$-D-glucosidase>$\beta$-D-galactosidase. In the seeds, $\alpha$-D-glucosidase activity was the highest and other glycosidases such as $\alpha$-D-galactosidase, $\beta$-D-glucosidase, and $\beta$-D-galactosidase were still significantly active. The $\alpha$-D-galactosidase in the grape flesh was purified over 83-folds through salting-out with $(NH_4)_2SO_4$ and a series of chromatographies employing Sephadex G-50, Octyl-Sepharose, Q-Sepha- rose, and Biogel P-100. The enzyme was a monomer of 45 kDs as determined through SDS-PAGE and Sephacryl S-200 chromatography. The purified enzyme showed a preference of $\alpha$-D-galactose to $\beta$-D-galactose as a substrate about 5.4 times. Sulfhydryl specific reagents such as N-ethylmaleimide and iodoacetamide significantly inhibited the enzyme activity to the extents of 48 and 52% of its initial activity, respectively. The optimumpH range of $\alpha$-D-galactosidase was around 6.5-7.0. The enzyme activity increased by 46% in the presence of 1mM $Fe^{2+}$.

• BMB Reports
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• v.37 no.4
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• pp.445-453
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• 2004

We identified apoptosis as being a significant mechanism of toxicity following the exposure of HeLa cell cultures to abrin holotoxin, which is in addition to its inhibition of protein biosynthesis by N-glycosidase activity. The treatment of HeLa cell cultures with abrin resulted in apoptotic cell death, as characterized by morphological and biochemical changes, i.e., cell shrinkage, internucleosomal DNA fragmentation, the occurrence of hypodiploid DNA, chromatin condensation, nuclear breakdown, DNA single strand breaks by TUNEL assay, and phosphatidylserine (PS) externalization. This apoptotic cell death was accompanied by caspase-9 and caspase-3 activation, as indicated by the cleavage of caspase substrates, which was preceded by mitochondrial cytochrome c release. The broad-spectrum caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD-fmk), prevented abrin-triggered caspase activation and partially abolished apoptotic cell death, but did not affect mitochondrial cytochrome c release. These results suggest that the release of mitochondrial cytochrome c, and the sequential caspase-9 and caspase-3 activations are important events in the signal transduction pathway of abrin-induced apoptotic cell death in the HeLa cell line.

• Advances in Traditional Medicine
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• v.3 no.3
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• pp.151-156
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• 2003

The leaves of Mirabilis jalapa L contains protein fraction presumed ribosome-inactivating protein (RIP). RIP is a group of protein that has RNA N-glycosidase activity that is capable to inhibit protein synthesis. Protein fraction of the plant was shown to be cytotoxic on HeLa cell-line, however, the mechanism by which the protein kill the cells is not identified yet, whether trough apoptosis, necrosis, or other mechanism. This research aim to study the mechanism of cell death caused by the protein fraction isolated from the leaves of this plant on HeLa and Raji cell-line, as representative of different kind of cancer cells. Results showed that protein fraction isolated from the leaves of Mirabilis jalapa L was more cytotoxic to HeLa cell-line (LC50: 0.65 mg/ml) than to Raji cell-line (1.815 mg/ml) on 48 hours incubation time. Moreover, it was demonstrated that the death of HeLa cells caused by the protein fraction was due to induction of apoptosis, while on Raji cell-line was due to non-apoptosis way, presumably via necrosis.

• Journal of Microbiology and Biotechnology
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• v.34 no.6
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• pp.1270-1275
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• 2024

Human gut bacterium Dorea sp. MRG-IFC3 is unique in that it is capable of metabolizing puerarin, an isoflavone C-glycoside, whereas it shows broad substrate glycosidase activity for the various flavonoid O-glycosides. To address the question on the substrate specificity, as well as biochemical characteristics, cell-free biotransformation of flavonoid glycosides was performed under various conditions. The results showed that there are two different enzyme systems responsible for the metabolism of flavonoid C-glycosides and O-glycosides in the MRG-IFC3 strain. The system responsible for the conversion of puerarin was inducible and comprised of two enzymes. One enzyme oxidizes puerarin to 3"-oxo-puerarin and the other enzyme converts 3"-oxo-puearin to daidzein. The second enzyme was only active toward 3"-oxo-puerarin. The activity of puerarin conversion to daidzein was enhanced in the presence of Mn²⁺ and NAD⁺. It was concluded that the puerarin C-deglycosylation by Dorea sp. MRG-IFC3 possibly adopts the same biochemical mechanism as the strain PUE, a species of Dorea longicatena.

• Korean Journal of Food Science and Technology
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• v.37 no.3
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• pp.377-388
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• 2005

Effects of silkworm powder addition on rheological properties of dough and quality characteristics of bread were investigated. Protein content of silkworm powder was 53,98%, much higher than 12.46% of wheat powder, Crude fiber, fat, and pretense contents of silkworm powder were higher than those of wheat flour, Acid analysis revealed glutamic acid content was highest 4,046.16 mg thus, significant depreciation of breadmaking was expected due to weakened gluten structure or dough. Addition of silkworm powder(optimum at 2%) with pretense inactivated by heat treatment resulted in significant improvement of volume and bread quality, with external and internal scores close to those of the control.

• BMB Reports
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• v.38 no.2
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• pp.225-231
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• 2005

Acid-labile subunit (ALS) is a component of the 150-kDa insulin-like growth factor-binding protein-3 (IGFBP-3) complex, which, by sequestering the majority of IGFs-I and -II and thereby prolonging the half-life of them in plasma, serves as a circulating reservoir of IGFs in mammalian species. A pGEX-2T plasmid and a baculovirus expression constructs harboring a coding sequence for glutathione-S transferase (GST)-porcine ALS (pALS) fusion protein were expressed in BL21(DE3) E. coli and Sf9 insect cells, respectively. The expressed protein was purified by glutathione or Ni-NTN affinity chromatography, followed by cleavage of the fusion protein using Factor Xa. In addition, pALS and hIGFBP-3 were also produced in small amounts in the Xenopus oocyte expression system which does not require any purification procedure. A 65-kDa pALS polypeptide was obtained following the prokaryotic expression and the enzymatic digestion, but biochemical characterization of this polypeptide was precluded because of an extremely low expression efficiency. The baculovirus-as well as Xenopus-expressed pALS exhibited the expected molecular mass of 85 kDa which was reduced into 75 and 65 kDa following deglycosylation of Asn-linked carbohydrates by Endo-F glycosidase, indicating that the expressed pALS was properly glycosylated. Moreover, irrespective of the source of pALS, the recombinant pALS and hIGFBP-3 formed a 130-kDa binary complex which could be immunoprecipitated by anti-hIGFBP-3 antibodies. Collectively, results indicate that an authentic pALS protein can be produced by the current expression systems.

• Parasites, Hosts and Diseases
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• v.48 no.2
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• pp.151-155
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• 2010

Allergen extracts from dust mites and cockroaches commonly found in Korean homes were used to evaluate their enzymatic activity as they are believed to influence allergenicity. Allergen extracts were prepared from 3 dust mite species (Dermatophagoides farinae, D. pteronyssinus, and Tyrophagus putrescentiae) and 3 cockroach species (Blattella germanica, Periplaneta americana, and P. fuliginosa) maintained in the Korea National Arthropods of Medical Importance Resource Bank. Proteins were extracted in PBS after homogenization using liquid nitrogen. The activities of various enzymes were investigated using the API Zym system. No significant difference in phosphatase, lipase, or glycosidase activity was observed among the 6 allergen extracts, but much difference was observed in protease activity. Protease activity was assessed in more detail by gelatin zymography and the EnzChek assay. Extract from T. putrescentiae showed the highest protease activity, followed by those of the cockroach extracts. Extracts from D. farinae and D. pteronyssinus showed only weak protease activity. Gelatinolytic activity was detected mainly in a 30-kDa protein in D. farinae, a 28-kDa protein in D. pteronyssinus, a > 26-kDa protein in T. putrescentiae, a > 20-kDa protein in B. germanica, and a > 23-kDa protein in P. americana and P. fuliginosa. The information on various enzymatic activities obtained in this study may be useful for future studies. In particular, the strong protease activity found in cockroach extracts could contribute to sensitization to cockroach allergens, which is known to be associated with the development of asthma.

• Journal of Ginseng Research
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• v.35 no.3
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• pp.344-351
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• 2011

Ginsenoside $Rb_1$ is the main component in ginsenosides. It is a protopanaxadiol-type ginsenoside that has a dammarane-type triterpenoid as an aglycone. In this study, ginsenoside $Rb_1$ was transformed into gypenoside XVII, ginsenoside Rd, ginsenoside $F_2$ and compound K by glycosidase from Leuconostoc mesenteroides DC102. The optimum time for the conversion was about 72 h at a constant pH of 6.0 to 8.0 and the optimum temperature was about $30^{\circ}C$. Under optimal conditions, ginsenoside $Rb_1$ was decomposed and converted into compound K by 72 h post-reaction (99%). The enzymatic reaction was analyzed by highperformance liquid chromatography, suggesting the transformation pathway: ginsenoside $Rb_1$ ${\rightarrow}$ gypenoside XVII and ginsenoside Rd${\rightarrow}$ginsenoside $F_2{\rightarrow}$compound K.

• Microbiology and Biotechnology Letters
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• v.34 no.4
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• pp.368-372
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• 2006

Quercetin is a flavonoid molecule that is known to tie in various sources of natural products such as vegetables and fruits. It has been proven that quercetin plays a crucial role in the prevention of colon cancer as well as homeostasis as radical scavenger in human body. It is also well-known that glycosidases, including $\alpha$-glucosidase, are involved in a variety of degenerative metabolic disorders. In the course of screening useful $\alpha$-glucosidase inhibitors, we screened out quercetin as a $\alpha$-glucosidase inhibitor from chemical libraries. Quercetin was shown to be a reversible, slow-binding, and noncompetitive inhibitor of yeast a-glucosidase with a K$_i$ value of $6.3\times10^{-8}$ M when it was included with an enzyme mixture. Together, these results show that quercetin has potential in treating disorders including diabetes, although the further mechanistic study is needed.