• Journal of the Korean Wood Science and Technology
• /
• 제28권4호
• /
• pp.29-40
• /
• 2000

Highly purified Cerrena unicolor laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) caused the demethoxylation of milled wood lignin and several lignin related substances. The constitutive form of the enzyme produced extracellularly by C. unicolor fermenter culture was isolated and purified by ion-exchange chromatography on the DEAE-Toyopearl column and by affinity chromatography on a ConA-Sepharose and Syringyl-AH-Sepharose 4B columns. The enzyme was further immobilized on functionalized porous glass (CPG) and keratin coated CPG. The demethylating activity was monitored both by estimation of released methanol and by detection of the level of methoxyl groups (also in some water miscible solvents) after incubation of lignin materials with laccase preparations (free and immobilized). The effects of the incubation time and temperature on the demethoxylating activity of immobilized laccase preparations were also studied.

• Molecules and Cells
• /
• 제26권3호
• /
• pp.228-235
• /
• 2008

Thiol-dependent redox systems are involved in regulation of diverse biological processes, such as response to stress, signal transduction, and protein folding. The thiol-based redox control is provided by mechanistically similar, but structurally distinct families of enzymes known as thiol oxidoreductases. Many such enzymes have been characterized, but identities and functions of the entire sets of thiol oxidoreductases in organisms are not known. Extreme sequence and structural divergence makes identification of these proteins difficult. Thiol oxidoreductases contain a redox-active cysteine residue, or its functional analog selenocysteine, in their active sites. Here, we describe computational methods for in silico prediction of thiol oxidoreductases in nucleotide and protein sequence databases and identification of their redox-active cysteines. We discuss different functional categories of cysteine residues, describe methods for discrimination between catalytic and noncatalytic and between redox and non-redox cysteine residues and highlight unique properties of the redox-active cysteines based on evolutionary conservation, secondary and three-dimensional structures, and sporadic replacement of cysteines with catalytically superior selenocysteine residues.

• Journal of Microbiology and Biotechnology
• /
• 제10권6호
• /
• pp.737-752
• /
• 2000

Wood-rotting basidiomycetous fungi are the most efficient degraders of lignin on earth. The white-rot fungus Phanerochaete chrysosporium has been used as a model microorganism in the study of enzymology and its application. Because of the ability of the white-rot fungus to degrade lignin, which has an irregular structure and large molecular mass, this fungus has also been studied in relation to degrading and mineralizing many environmental pollutants. The fungus includes an array of enzymes, such as lignin peroxidase (LiP), manganese-dependent peroxidase (MnP), cellobiose:quinone oxidoreductase, and $H_2O_2$-producing enzymes and also produces many other components of the ligninolytic system, such as veratryl alcohol (VA) and oxalate. In addition, the fungus has mechanisms for the reduction of degradation intermediates. The ligninolytic systems have been proved to provide reductive reactions as well as oxidative reactions, both of which are essential for the degradation of lignin and organopollutants. Further study on the white-rot fungus may provide many tools to both utilize lignin, the most abundant aromatic polymer, and bioremediate many recalcitrant organopollutants.

• Journal of Microbiology and Biotechnology
• /
• 제28권8호
• /
• pp.1346-1351
• /
• 2018

Oxidoreductases are effective biocatalysts, but their practical use is limited by the need for large quantities of NAD(P)H. In this study, a whole-cell biocatalyst for NAD(P)H cofactor regeneration was developed using the economical substrate glycerol. This cofactor regeneration system employs permeabilized Escherichia coli cells in which the glpD and gldA genes were deleted and the gpsA gene, which encodes $NAD(P)^+-dependent$ glycerol-3-phosphate dehydrogenase, was overexpressed. These manipulations were applied to block a side reaction (i.e., the conversion of glycerol to dihydroxyacetone) and to switch the glpD-encoding enzyme reaction to a gpsA-encoding enzyme reaction that generates both NADH and NADPH. We demonstrated the performance of the cofactor regeneration system using a lactate dehydrogenase reaction as a coupling reaction model. The developed biocatalyst involves an economical substrate, bifunctional regeneration of NAD(P)H, and simple reaction conditions as well as a stable environment for enzymes, and is thus applicable to a variety of oxidoreductase reactions requiring NAD(P)H regeneration.

• BMB Reports
• /
• 제37권2호
• /
• pp.139-143
• /
• 2004

The antioxidant responsive element (ARE) is a cis-acting regulatory element of genes encoding phase II detoxification enzymes and antioxidant proteins, such as NAD(P)H: quinone oxidoreductase 1, glutathione S-transferases, and glutamate-cysteine ligase. Interestingly, it has been reported that Nrf2 (NF-E2-related factor 2) regulates a wide array of ARE-driven genes in various cell types. Nrf2 is a basic leucine zipper transcription factor, which was originally identified as a binding protein of locus control region of ss-globin gene. The DNA binding sequence of Nrf2 and ARE sequence are very similar, and many studies demonstrated that Nrf2 binds to the ARE sites leading to up-regulation of downstream genes. The function of Nrf2 and its downstream target genes suggests that the Nrf2-ARE pathway is important in the cellular antioxidant defense system. In support of this, many studies showed a critical role of Nrf2 in cellular protection and anti-carcinogenicity, implying that the Nrf2-ARE pathway may serve as a therapeutic target for neurodegenerative diseases and cancers, in which oxidative stress is closely implicated.

• Journal of Microbiology
• /
• 제42권2호
• /
• pp.139-142
• /
• 2004

To identify genes involved in the decolorization of brilliant green, we isolated random mutants generated by transposon insertion in brilliant green-decolorizing bacterium, Citrobacter sp. The resulting mutant bank yielded 19 mutants with a complete defect in terms of the brilliant green color removing ability. Southern hybridization with a Tn5 fragment as a probe showed a single hybridized band in 7 mutants and these mutants appeared to have insertions at different sites of the chromosome. Tn5-inserted genes were isolated and the DNA sequence flanking Tn5 was determined. By comparing these with a sequence database, putative protein products encoded by bg genes were identified as follows: bg 3 as a LysR-type regulatory protein; bg 11 as a MalG protein in the maltose transport system; bg 14 as an oxidoreductase; and bg 17 as an ABC transporter. The sequences deduced from the three bg genes, bg 2, bg 7 and bg 16, showed no significant similarity to any protein with a known function, suggesting that these three bg genes may encode unidentified proteins responsible for the decolorization of brilliant green.

• Animal Bioscience
• /
• 제34권6호
• /
• pp.1006-1013
• /
• 2021

Objective: Cells have increased susceptibility to activation of apoptosis when suffering heat stress (HS). An effective supplementation strategy to mimic heat-induced apoptosis of bovine mammary epithelial cells (MECs) is necessary to maintain optimal milk production. This study aimed to investigate possible protective effects of the anti-apoptotic activity of 5-aminolevulinic acid (5-ALA) against HS-induced damage of bovine MECs. Methods: Bovine MECs were pretreated with or without 5-ALA at concentrations of 10, 100, and 500 µM for 24 h followed by HS (42.5℃ for 24 h and 48 h). Cell viability was measured with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Real-time quantitative polymerase chain reaction and Western blotting were used to explore the regulation of genes associated with apoptosis, oxidative stress, and endoplasmic reticulum (ER) stress genes. Results: We found that 5-ALA induces cytoprotection via inhibition of apoptosis markers after HS-induced damage. Pretreatment of bovine MECs with 5-ALA resulted in dramatic upregulation of mRNA for nuclear factor erythroid-derived 2-like factor 2, heme oxygenase-1, and NAD(P)H quinone oxidoreductase 1, all of which are antioxidant stress genes. Moreover, 5-ALA pretreatment significantly suppressed HS-induced ER stress-associated markers, glucose-regulated protein 78, and C/EBP homologous protein expression levels. Conclusion: 5-ALA can ameliorate the ER stress in heat stressed bovine MEC via enhancing the expression of antioxidant gene.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
• /
• pp.330.2-330.2
• /
• 2002

The conformational study on cyclic Ac-Cys-Pro-Xaa-Cys-NHMe (Ac-CPXC-NHMe: X = Ala, Val. Leu. Aib. Gly. His. Phe, Tyr. Asn. and Ser) peptides has been carried out using the ECEPP/3 force field and the hydration shell model in the unhydrated and hydrated states. This work has been undertaken to investigate structural implications of the CPXC sequence as the chain reversal for the initiation of protein folding and as the motif for active site of disulfide oxidoreductases. The backbone conformation DAAA is in common the most feasible for cyclic CPXC peptides in the hydrated state. which has a type 1${\beta}$-turn at the Pro-Xaa sequence. The proline residue and the hydrogen bond between backbones of two cystines appear to play a role in stabilizing this preferred conformation of cycilc CPXC peptides. However. the distributions of backbone conformations and ${\beta}$-turns may indicate that the cyclic CPXC peptide seems to exist as an ensemble of ${\beta}$-turns and coiled conformations. The intirnsic stability of the cyclic CPXC motif itself the active conformation appears to play a role in determining electrochemical properties of disulfide oxidoreductases.

• Parasites, Hosts and Diseases
• /
• 제59권1호
• /
• pp.67-76
• /
• 2021

Legionella pneumophila is an opportunistic pathogen that survives and proliferates within protists such as Acanthamoeba spp. in environment. However, intracellular pathogenic endosymbiosis and its implications within Acanthamoeba spp. remain poorly understood. In this study, RNA sequencing analysis was used to investigate transcriptional changes in A. castellanii in response to L. pneumophila infection. Based on RNA sequencing data, we identified 1,211 upregulated genes and 1,131 downregulated genes in A. castellanii infected with L. pneumophila for 12 hr. After 24 hr, 1,321 upregulated genes and 1,379 downregulated genes were identified. Gene ontology (GO) analysis revealed that L. pneumophila endosymbiosis enhanced hydrolase activity, catalytic activity, and DNA binding while reducing oxidoreductase activity in the molecular function (MF) domain. In particular, multiple genes associated with the GO term 'integral component of membrane' were downregulated during endosymbiosis. The endosymbiont also induced differential expression of various methyltransferases and acetyltransferases in A. castellanii. Findings herein are may significantly contribute to understanding endosymbiosis of L. pneumophila within A. castellanii.

• 대한의생명과학회지
• /
• 제27권4호
• /
• pp.277-282
• /
• 2021

Hydrocotyle is a genus of prostrate, perennial aquatic or semi-aquatic plants formerly classified in the family Apiaceae, now in the family Araliaceae. Lipoxygenases (LOX) are present in the human body and play an important role in the stimulation of inflammatory reactions. Ethanolic extracts of five Hydrocotyle species (H. ramiflora, H. maritima, H. nepalensis, H. sibthorpioides, and H. yabei) showed inhibition of 23.5~50.6% at 2.0 mg/mL. Their extracts showed LOX inhibition in half maximal effective concentration (EC₅₀) range 15.1~15.7 ㎍/mL. Hyaluronic acid is a glycosaminoglycan, a major component of the extracellular matrix Five extracts of these species inhibited less than 23.0% of Hyaluronidase (HAase) activity at a concentration of 2.0 mg/mL Xanthine oxidase (XO) is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species. Five Hydrocotyle species were found to have inhibitory activity of XO at 2.0 mg/ml, with 65% having greater than 50% inhibition. H. ramiflora exhibited the highest activity with an inhibition of 80.0%. The results suggested that Lipoxygenases, Hyaluronidase, and Busan 47340, Republic of Korea from five Hydrocotyle species might be multifunctional and prevent the degradation of allergic reactions and inflammation.