Biomedical subjects

Tomoaki Nishida

Publications and source records attributed to Tomoaki Nishida.

15 recordsLinked to original sources

PubMed2006

Role of 1-hydroxybenzotriazole in oxidation by laccase from Trametes versicolor. Kinetic analysis of the laccase-1-hydroxybenzotriazole couple.

In the current studies, we used Lineweaver-Burke analysis to examine the role of 1-hydroxybenzotriazole (HBT) in the oxidation of various compounds by laccase from Trametes versicolor. At low concentrations, HBT was a competitive inhibitor of the oxidation, but at high concentrations, it was a noncompetitive inhibitor. Analysis of the oxidation of ferrocytochrome c by the laccase-HBT couple showed that increasing the concentration of ferrocytochrome c did not affect the V(max) but reduced the apparent K(m). In addition, in the manganese peroxidase-Mn(II) reaction, which is a typical oxidation system by mediator, the apparent K(m) and V(max) increased as the concentration of the substrate 2,6-dimethoxyphenol was increased. These results indicate that HBT is involved in the binding of laccase and substrates that laccase cannot oxidize alone.

Basidiomycota↗

PubMed2006

The cationic cell-wall-peroxidase having oxidation ability for polymeric substrate participates in the late stage of lignification of Populus alba L.

Previously we reported that purified Cell Wall Peroxidase-Cationic (CWPO-C) from poplar callus (Populus alba L.) oxidizes sinapyl alcohol and polymeric substrate unlike other plant peroxidases and proposed that this isoenzyme is a conceivable lignification specific peroxidase. In this study, we cloned full-length cDNA of CWPO-C and investigated the transcription of CWPO-C gene in various organs and the localization of CWPO-C protein in the differentiating xylem of poplar stem.Real-time PCR analyses indicated that CWPO-C gene is constitutively expressed in the developing xylem, leaf, and shoot but not affected by many stress treatments. Immunohistochemical analysis showed that CWPO-C locates in the middle lamellae, cell corners, and secondary cell walls of the fiber cells during the lignification. The intensity of the CWPO-C labeling increased gradually from the cell wall thickening stage to mature stage of fiber cells, which is very consistent with the increase of lignin content in the developing xylem. These results strongly support that CWPO-C is responsible for the lignification of the secondary xylem. Interestingly, immuno-labeling of CWPO-C was also observed inside of the ray parenchyma cells instead no signals were detected within the developing fiber cells. This suggests that CWPO-C is biosynthesized in the parenchyma cells and provided to the middle lamellae, the cell corners, and the cell walls to achieve lignin polymerization.

Amino Acid Sequence↗

PubMed2006

Isolation and characterization of a novel bacterium, Sphingomonas bisphenolicum strain AO1, that degrades bisphenol A.

Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, BPA), which is used as a synthetic resin material or a plasticizer, is a pollutant that possesses endocrine-disrupting activity. Bioremediation of BPA is used to decrease its polluting effects, and here we report a novel bacterial strain AO1, which is able to degrade BPA. This strain was isolated using enrichment cultivation from a soil sample from a vegetable-growing field; the sample was one of 500 soil samples collected across Japan. Strain AO1 degraded 100 mg/l BPA to an undetectable level within 6 h in MYPG medium (containing malt extract, yeast extract, peptone, and glucose) and within 48 h in minimum medium containing 1% glucose at 30 degrees C. Strain AO1 can utilize BPA as a sole source of carbon and as an energy source under aerobic conditions. The estrogenic activity of BPA in MYPG medium was ultimately reduced by strain AO1, although the activity initially increased. Taxonomical analysis showed that strain AO1 is closely related to Sphingomonas chlorophenolicum and S. herbicidovorans, neither of which have a capacity for BPA degradation. DNA-DNA hybridization showed that strain AO1 is a novel species of the Sphingomonas genus, and we designated AO1 as S. bisphenolicum.

Benzhydryl Compounds↗

PubMed2006

Removal of estrogenic activity of natural steroidal hormone estrone by ligninolytic enzymes from white rot fungi.

Natural steroidal hormone estrone (E1) was treated with the white rot fungus Phanerochaete sordida YK-624 under ligninolytic condition with low-nitrogen and high-carbon culture medium. E1 decreased by 98% after 5 d of treatment and the activities of ligninolytic enzymes, manganese peroxidase (MnP) and laccase, were detected during treatment, which suggested that the disappearance of E1 is related to ligninolytic enzymes produced extracellularly by white rot fungus. Therefore, E1 was treated with MnP and laccase prepared from the culture of white rot fungi. HPLC analysis demonstrated that E1 disappeared completely in the reaction mixture after 1 h of treatment with either MnP or laccase. Using the yeast two-hybrid assay system, it was also confirmed that both enzymatic treatments completely removed the estrogenic activity of E1 after 2 h. These results strongly suggest that ligninolytic enzymes are effective in removing the estrogenic activity of E1.

Chromatography, High Pressure Liquid↗

PubMed2005

Characteristics of novel lignin peroxidases produced by white-rot fungus Phanerochaete sordida YK-624.

We characterized a lignin peroxidase (YK-LiP2) isolated from shaking culture inoculated with the white-rot fungus Phanerochaete sordida YK-624. The YK-LiP2 enzyme was identified and purified to homogeneity by anion-exchange chromatography and gel permeation chromatography. The molecular weight of YK-LiP2 was approximately 45 kDa, and its absorption spectrum was almost the same as that of the LiP (Pc-LiP) from P. chrysosporium. Steady-state kinetics of veratryl alcohol (VA) oxidation by YK-LiP2 revealed an ordered bi-bi ping-pong mechanism, although the Pc-LiP oxidation of ferrocytochrome c obeys peroxidase ping-pong kinetics rather than ordered bi-bi ping-pong kinetics. Degradation of dimeric lignin model compounds by YK-LiP2 was more effective than that by Pc-LiP. Moreover, YK-LiP2 and YK-LiP1, which was previously isolated from static culture inoculated with P. sordida YK-624, oxidized VA under a higher concentration of hydrogen peroxide (>2.5 mM) although Pc-LiP could not oxidize VA in the presence of 2.5 mM hydrogen peroxide.

Benzyl Alcohols↗

PubMed2005

Removal of estrogenic activity of endocrine-disrupting genistein by ligninolytic enzymes from white rot fungi.

Endocrine-disrupting genistein was treated with the white rot fungus Phanerochaete sordida YK-624 under ligninolytic condition with low-nitrogen and high-carbon culture medium. Genistein decreased by 93% after 4 days of treatment and the activities of ligninolytic enzymes, manganese peroxidase (MnP) and laccase, were detected during treatment, thus suggesting that the disappearance of genistein is related to ligninolytic enzymes produced extracellularly by white rot fungi. Therefore, genistein was treated with MnP, laccase, and the laccase-mediator system with 1-hydroxybenzotriazole (HBT) as a mediator. HPLC analysis demonstrated that genistein disappeared almost completely in the reaction mixture after 4 h of treatment with either MnP, laccase, or the laccase-HBT system. Using the yeast two-hybrid assay system, it was also confirmed that three enzymatic treatments completely removed the estrogenic activity of genistein after 4h. These results strongly suggest that ligninolytic enzymes are effective in removing the estrogenic activity of genistein.

Animals↗

PubMed2004

Three-component coupling based on the "cation pool" method.

Sequential one-pot three-component coupling reactions have been developed based on the "cation pool" method. An N-acyliminium ion generated by the "cation pool" method adds to an electron-rich carbon-carbon double bond, such as enamine derivatives and vinyl sulfides, to form the second "cation pool". The addition of nucleophiles such as allylsilanes, enol silyl ethers, Grignard reagents, and organoaluminum compounds led to the formation of the corresponding three-component coupling products.

Journal Article↗

PubMed2004

4-Coumarate:coenzyme A ligase in black locust (Robinia pseudoacacia) catalyses the conversion of sinapate to sinapoyl-CoA.

4-Coumarate:coenzyme A (CoA) ligase (4CL, EC 6.2.1.12) in crude enzyme preparation from the developing xylem of black locust (Robinia pseudoacacia) converted sinapate to sinapoyl CoA. The sinapate-converting activity was not inhibited by other cinnamate derivatives, such as p-coumarate, caffeate or ferulate, in the mixed-substrate assay. The crude extract prepared from the developing xylem was separated by anion-exchange chromatography into three different 4CL isoforms. The isoform 4CL1 had a strong substrate preference for p-coumarate, but lacked the activity for ferulate and sinapate. On the other hand, 4CL2 and 4CL3 displayed activity toward sinapate and also possessed high activity toward caffeate as well as p-coumarate. The crude extract from the shoots exhibited a very similar substrate preference to that of the developing xylem; therefore, 4CL2 may be a major isoform in both crude enzyme preparations. These results support the hypothesis that sinapate-converting 4CL isoform is constitutively expressed in lignin-forming cells.

Acyl Coenzyme A↗

PubMed2004

Lignin peroxidase is involved in the biobleaching of manganese-less oxygen-delignified hardwood kraft pulp by white-rot fungi in the solid-fermentation system.

Biobleaching of manganese-less oxygen-delignified hardwood kraft pulp (E-OKP) by the white-rot fungi Phanerochaete sordida YK-624 and P. chrysosporium was examined in the solid-state fermentation system. P. sordida YK-624 possessed a higher brightening activity than P. chrysosporium, increasing pulp brightness by 13.4 points after seven days of treatment. In these fermentation systems, lignin peroxidase (LiP) activity was detected as the principle ligninolytic enzyme, and manganese peroxidase and laccase activities were scarcely detected over the course of treatment of E-OKP by either fungus. Moreover, a linear relationship between brightness increase and cumulative LiP activity was observed under all tested culture conditions with P. sordida YK-624 and P. chrysosporium. These results indicated that LiP is involved in the brightening of E-OKP by both white-rot fungi.

Fermentation↗

PubMed2004

Lignin dehydrogenative polymerization mechanism: a poplar cell wall peroxidase directly oxidizes polymer lignin and produces in vitro dehydrogenative polymer rich in beta-O-4 linkage.

An investigation was performed to determine whether lignin dehydrogenative polymerization proceeds via radical mediation or direct oxidation by peroxidases. It was found that coniferyl alcohol radical transferred quickly to sinapyl alcohol. The transfer to syringaresinol was slower, however, the transfer to polymeric lignols occurred very slightly. This result suggests that the radical mediator theory does not sufficiently explain the mechanism for dehydrogenative polymerization of lignin. A cationic cell wall peroxidase (CWPO-C) from poplar (Populus alba L.) callus showed a strong substrate preference for sinapyl alcohol and the sinapyl alcohol dimer, syringaresinol. Moreover, CWPO-C was capable of oxidizing high-molecular-weight sinapyl alcohol polymers and ferrocytochrome c. Therefore, the CWPO-C characteristics are important to produce polymer lignin. The results suggest that CWPO-C may be a peroxidase isoenzyme responsible for the lignification of plant cell walls.

Alcohols↗

PubMed2004

Degradation of the antifouling compound Irgarol 1051 by manganese peroxidase from the white rot fungus Phanerochaete chrysosporium.

Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine), a derivative of s-triazine herbicide, is an antifouling compound used as an alternative to organotins. The compound is highly persistent and is known to be biodegraded only by the white rot fungus, Phanerochaete chrysosporium. We used partially purified manganese peroxidase (MnP) prepared from P. chrysosporium to evaluate its capacity to degrade Irgarol 1051. MnP degraded Irgarol 1051 to two major products, one identified as M1 (identical to GS26575, 2-methylthio-4-tert-butylamino-6-amino-s-triazine) and the other not identified but with same mass spectrum as M1 and a different ultraviolet spectrum. This report clearly demonstrates that this ligninolytic enzyme is involved in the degradation of Irgarol 1051.

Biodegradation, Environmental↗

PubMed2004

Oxidative dechlorination of methoxychlor by ligninolytic enzymes from white-rot fungi.

Ligninolytic enzymes, manganese peroxidase (MnP), laccase, and lignin peroxidase (LiP), from white-rot fungi were used in an attempt to treat methoxychlor (MC), a chemical widely used as a pesticide. MnP and laccase in the presence of Tween 80 and 1-hydroxybenzotriazole (HBT), respectively, and LiP were found to degrade MC, and MnP-Tween 80 decreased MC levels by about 65% after a 24-h treatment. MC was converted into methoxychlor olefin (MCO) and 4,4'-dimethoxybenzophenone by MnP-Tween 80 or laccase-HBT treatment. These results indicate that ligninolytic enzymes from white-rot fungi can catalyze the oxidative dechlorination of MC. Moreover, a metabolite MCO was also degraded by MnP-Tween 80 or laccase-HBT treatment.

Gas Chromatography-Mass Spectrometry↗

PubMed2003

Purification and characterization of a novel lignin peroxidase from white-rot fungus Phanerochaete sordida YK-624.

We characterized kinetics and substrate oxidation of a novel lignin peroxidase (YK-LiP) isolated from white-rot fungus Phanerochaete sordida YK-624. YK-LiP enzyme was identified and purified to homogeneity by anion-exchange chromatography and gel permeation chromatography. The molecular mass of YK-LiP was approximately 50 kDa, and the absorption spectrum of YK-LiP was almost the same as that of the LiP (Pc-LiP) from Phanerochaete chrysosporium. Steady-state kinetics of veratryl alcohol oxidation by YK-LiP (unlike that by Pc-LiP) revealed a bi-reactant sequential mechanism, although reactivity of YK-LiP to various monomeric substituted aromatic compounds was similar to that of Pc-LiP. Degradation of dimeric lignin model compounds was more effective by YK-LiP than by Pc-LiP, and the oxidation rate of sinapyl alcohol oligomer by YK-LiP was much faster than that by Pc-LiP.

Acrolein↗

PubMed2003

Removal of estrogenic activities of 17beta-estradiol and ethinylestradiol by ligninolytic enzymes from white rot fungi.

We investigated whether manganese peroxidase (MnP) and the laccase-mediator system with 1-hydroxybenzotriazole (HBT) as mediator can remove the estrogenic activities of the steroidal hormones 17beta-estradiol (E(2)) and ethinylestradiol (EE(2)). Using the yeast two-hybrid assay system, we confirmed that the estrogenic activities of E(2) and EE(2) are much higher than those of bisphenol A and nonylphenol. Greater than 80% of the estrogenic activities of E(2) and EE(2) were removed following 1-h treatment with MnP or the laccase-HBT system; extending the treatment time to 8h removed the remaining estrogenic activity of both steroidal hormones. HPLC analysis demonstrated that E(2) and EE(2) had disappeared almost completely in the reaction mixture after a 1-h treatment. These results strongly suggest that these ligninolytic enzymes are effective in removing the estrogenic activities of E(2) and EE(2).

Bioreactors↗

PubMed2002

NADH oxidation by manganese peroxidase with or without alpha-hydroxy acid.

NADH oxidation by manganese peroxidase (MnP) was done in a reaction mixture including either alpha-hydroxy acid or acetate. The oxidation in the former reaction mixture was inhibited by a catalase and was accelerated by exogenous H2O2, while the oxidation in the latter reaction mixture was inhibited by a superoxide dismutase and was not accelerated by the exogenous H2O2. These results indicated that there are significant differences between the two reaction systems, particularly, in the active oxygen species involved in the reactions. Additionally, the experiment of MnP reduction with Mn(II) suggests that MnP has a separate catalytic activity other than an oxidation of Mn(II) to Mn(III) in the reaction mixture including acetate.

Acetates↗