48 Matching Results

Search Results

Advanced search parameters have been applied.

The Quantum Mixed-Spin Heme State of Barley Peroxidase: A Paradigm for Class III Peroxidases

Description: Electronic absorption and resonance Raman (RR) spectra of the ferric form of barley grain peroxidase (BP 1) at various pH values both at room temperature and 20 K are . reported, together with EPR spectra at 10 K. The ferrous forms and the ferric complex with fluoride have also been studied. A quantum mechanically mixed-spin (QS) state has been identified. The QS heme species co-exists with 6- and 5-cHS heroes; the relative populations of these three spin states are found to be dependent on pH and temperature. However, the QS species remains in all cases the dominant heme spin species. Barley peroxidase appears to be further characterized by a splitting of the two vinyl stretching modes, indicating that the vinyl groups are differently conjugated with the porphyrin. An analysis of the presently available spectroscopic data for proteins from all three peroxidase classes suggests that the simultaneous occurrence of the QS heme state as well as the splitting of the two vinyl stretching modes is confined to class III enzymes. The former point is discussed in terms of the possible influences of heme deformations on heme spin state. It is found that moderate saddling alone is probably not enough to cause the QS state, although some saddling maybe necessary for the QS state.
Date: March 23, 1999
Creator: Howes, B.D.; Ma, J.; Marzocchi, M.P.; Schiodt, C.B.; Shelnutt, J.A.; Smulevich, G. et al.
Partner: UNT Libraries Government Documents Department

A study of over production and enhanced secretion of enzymes. Quarterly report 1

Description: The current project is concerned with the over-production and enhanced secretion of PPO, cellulase and lignin peroxidase. The project is divided into two segments: over-production of lignocellulolytic enzymes by genetic engineering methodologies and hyper-production and enhanced secretion of these enzymes by biochemical/electron microscopical techniques. The former approach employs recombinant DNA procedures, ligation of appropriate nuclease generated DNA fragments into a vector and the subsequent transformation of Escherichia coli to yield E. coli harboring a C. versicolor DNA insert. The biochemistry/electron microscopical method involves substrate induction and the time-dependent addition of respiration and PPO inhibitors to elevate C.versicolor`s ability to synthesize and secrete lignocellulosic enzymes. In this connection, cell fractionation/kinetic analysis, TEM immunoelectron microscopic localization and TEM substrate localization of PPO are being employed to assess the route of secretion. Both approaches will culminate in the batch culture of either E. coli or C. versicolor, in a fermentor with the subsequent development of rapid isolation and purification procedures to yield elevated quantities of pure lignocellulosic enzymes. During the past year, research effort were directed toward determining the route of polyphenol oxidase (PPO) secretion by the wood-decay fungus, Coriolus versicolor. In addition, research activities were continued to over-produce and to purify PPO as well as define the time-dependent intra- and extra-cellular appearances of C. versicolor ligninases and cellulases.
Date: December 28, 1992
Creator: Dashek, W.V.
Partner: UNT Libraries Government Documents Department

Regulation of Coal Polymer Degradation by Fungi

Description: During this reporting period we have further studied the oxidation of soluble coal macromolecules by lignin peroxidase from Phanerochaete chrysosporium . Previous studies by others have suggested that a soluble fraction (coal macromolecule B-111) from a nitric acid solubilized North Dakota Lignite is depolymerized by this enzyme. Our investigations indicate that fraction B-111 is a substrate for lignin peroxidase as this material is decolorized in the presence of lignin peroxidase H8 and hydrogen peroxide. Of interest, however, is the observation that little, if any, depolymerization of this material occurs. Instead, it appears that lignin peroxidase and coal macromolecule B-111 form a precipitate. These results are similar to those observed in our investigations of lignin peroxidase mediated oxidation of oxalate solubilize coal macromolecule. Previous studies in our laboratory using a spectrophotometric assay suggested that, in addition to oxalate, several other fungal metabolites are able to solubilize leonardite. We have reinvestigated this phenomenon using a more reliable gravimetric procedure for assessing solubilization. Our results confirm our earlier findings that malate, oxaloacetate and citrate are effective solubilizing agents whereas succinate, fumarate and x-ketoglutarate solubilize relatively small amounts of leonardite. Finally, we have studied the composition of the insoluble material remaining following extensive solubilization by sodium oxalate. The ratio of hydrogen to carbon is increased in the insoluble material relative to the parent leonardite. However, the ratio of oxygen to carbon is also increased in the insoluble material. Thus, the insoluble material does not appear to be more highly reduced that the parent leonardite and is not likely to be a better fuel that the parent material.
Date: September 1998
Partner: UNT Libraries Government Documents Department

Surface plasmon enhanced interfacial electron transfer and resonance Raman, surface-enhanced resonance Raman studies of cytochrome C mutants

Description: Surface plasmon resonance was utilized to enhance the electron transfer at silver/solution interfaces. Photoelectrochemical reductions of nitrite, nitrate, and CO{sub 2} were studied on electrochemically roughened silver electrode surfaces. The dependence of the photocurrent on photon energy, applied potential and concentration of nitrite demonstrates that the photoelectrochemical reduction proceeds via photoemission process followed by the capture of hydrated electrons. The excitation of plasmon resonances in nanosized metal structures resulted in the enhancement of the photoemission process. In the case of photoelectrocatalytic reduction of CO{sub 2}, large photoelectrocatalytic effect for the reduction of CO{sub 2} was observed in the presence of surface adsorbed methylviologen, which functions as a mediator for the photoexcited electron transfer from silver metal to CO{sub 2} in solution. Photoinduced reduction of microperoxidase-11 adsorbed on roughened silver electrode was also observed and attributed to the direct photoejection of free electrons of silver metal. Surface plasmon assisted electron transfer at nanostructured silver particle surfaces was further determined by EPR method.
Date: November 8, 1999
Creator: Zheng, Junwei
Partner: UNT Libraries Government Documents Department

Calcium-Dependent Conformation of a Heme and Fingerprint Peptide of the Di-Heme Cytochrome c Peroxidase from Paracoccus Pantotrophus

Description: The structural changes in the heme macrocycle and substituents caused by binding of Ca{sup 2+} to the diheme cytochrome c peroxidase from Paracoccuspantotrophus were clarified by resonance Raman spectroscopy of the inactive filly oxidized form of the enzyme. The changes in the macrocycle vibrational modes are consistent with a Ca{sup 2+}-dependent increase in the out-of-plane distortion of the low-potential heme, the proposed peroxidatic heme. Most of the increase in out-of-plane distortion occurs when the high affinity site I is occupied, but a small further increase in distortion occurs when site II is also occupied by Ca{sup 2+}or Mg{sup 2+}. This increase in the heme distortion also explains the red shift in the Soret absorption band that occurs upon Ca{sup 2+} binding. Changes also occur in the low frequency substituent modes of the heme, indicating that a structural change in the covalently attached fingerprint pentapeptide of the LP heme occurs upon CM{sup 2+} binding to site I. These structural changes, possibly enhanced in the semi-reduced form of the enzyme, may lead to loss of the sixth ligand at the peroxidatic heme and activation of the enzyme.
Date: December 18, 2000
Creator: PAULETA,SOFIA R.; LU,YI; GOODHEW,CELIA F.; MOURA,ISABEL; PETTIGREW,GRAHAM W. & SHELNUTT,JOHN A.
Partner: UNT Libraries Government Documents Department

Regulation of coal polymer degradation by fungi. Eighth quarterly report, [April--June 1996]

Description: This project addresses the solubilization of low-rank coal (leonardite) by lignin degrading fungi. During this reporting period efforts were focused on determining the effect of pH on coal solubilization by oxalate ion and other biologically important compounds that might function as metal chelators, on the role of laccase in coal solubilization and metabolism, on decolorization of soluble coal macromolecule by Phanerochaete chrysosporium and T. versicolor in solid agar media, and on solubilization of coal in slurry cultures and solid phase reactors.
Date: July 28, 1996
Creator: Irvine, R.L. & Bumpus, J.A.
Partner: UNT Libraries Government Documents Department

Mechanisms of lignin biosynthesis during xylogenesis in Zinnia elegans. Final report, July 1, 1992--June 30, 1996

Description: This project initially focused on identifying and characterizing three components of the extracellular lignification reaction: peroxidases, hydrogen peroxide production, and oxygen dependent oxidases. Zinnia elegans was utilized for the model organism. Laccase activity was found to be more tightly correlated with lignification than peroxidase activity.
Date: May 1, 1997
Creator: Eriksson, K.E.L. & Dean, J.F.D.
Partner: UNT Libraries Government Documents Department

UTSI/CFFF MHD Program Completion and Related Activities.

Description: During this reporting period we have further studied the oxidation of soluble coal macromolecules by lignin peroxidase from Phanerochaete chrysosporium. Previous studies by others have suggested that a soluble fraction (coal macromolecule B-111) from a nitric acid solubilized North Dakota Lignite is depolymerized by this enzyme. Our investigations indicate that fraction B-111 is a substrate for lignin peroxidase as this material is decolorized in the presence of lignin peroxidase H{sub 8} and hydrogen peroxide. Of interest, however, is the observation that little, if any, depolymerization of this material occurs. Instead, it appears that lignin peroxidase and coal macromolecule B-111 form a precipitate. These results are similar to those observed in our investigations of lignin peroxidase mediated oxidation of oxalate solubilize coal macromolecule. Previous studies in our laboratory using a spectrophotometric assay suggested that, in addition to oxalate, several other fungal metabolites are able to solubilize leonardite. We have reinvestigated this phenomenon using a more reliable gravimetric procedure for assessing solubilization. Our results confirm our earlier findings that malate, oxaloacetate and citrate are effective solubilizing agents whereas succinate, fumarate and {alpha}-ketoglutarate solubilize relatively small amounts of leonardite. Finally, we have studied the composition of the insoluble material remaining following extensive solubilization by sodium oxalate. The ratio of hydrogen to carbon is increased in the insoluble material relative to the parent leonardite. However, the ratio of oxygen to carbon is also increased in the insoluble material. Thus, the insoluble material does not appear to be more highly reduced that the parent leonardite and is not likely to be a better fuel that the parent material.
Date: October 31, 1997
Creator: Irvin, R.L. & Bumpus, J.A.
Partner: UNT Libraries Government Documents Department

The molecular characterization of the lignin-forming peroxidase. Progress summary report, April 1, 1992--March 31, 1995

Description: My research program focuses entirely on the study of the lignin-forming peroxidase of tobacco. Ever since our cloning and sequencing of the first plant peroxidase cDNA, we have pioneered in the introduction of the tools of molecular biology to the study of plant peroxidases. A significant part of our effort has been focused on the construction and analysis of transgenic plants which either over- or under-express the tobacco anionic peroxidase. This research has not only supported the role for this enzyme in lignification, but has opened the door to our understanding of additional metabolic functions including auxin metabolism and insect defense. As you will learn, this enzyme`s role in auxin catabolism has lead to numerous phenotypes in transgenic plants. More recently, our attention has been directed towards the analysis of peroxidase gene expression. From this work we have learned that the anionic peroxidase gene is expressed at high levels in the xylem-forming cells, epidermis, and trichomes. This expression pattern supports its role lignification and hose defenses. We have also learned that this gene is down-regulated by auxin which indicates a strong relationship between auxin and the anionic peroxidase. 12 figs.
Date: June 1, 1995
Creator: Lagrimini, L.M.
Partner: UNT Libraries Government Documents Department

Identification of the primary mechanism for fungal lignin degradation. Progress report

Description: Many lignin-degrading fungi appear to lack lignin peroxidase (LiP), an enzyme generally thought important for fungal ligninolysis. The authors are working with one of these fungi, Ceriporiopsis subvermispora, an aggressive white-rotter that selectively removes lignin from wood. During this project period, they have obtained the following principal results: new polymeric lignin model compounds were developed to assist in the elucidation of fungal ligninolytic mechanisms; experiments with one of the polymeric lignin models showed that C. subvermispora cultures which express no detectable LiP activity are nevertheless able to degrade nonphenolic lignin structures, this result is significant because LiPs were previously considered essential for fungal attack on these recalcitrant structures, which constitute about 90% of lignin; manganese peroxidases (MnPs), which C. subvermispora does produce, catalyze the peroxidation of unsaturated fatty acids to give fatty acid hydroperoxides, fatty acid hydroperoxides are also used by MnP as oxidants (in place of H{sub 2}O{sub 2}) that support the MnP catalytic cycle, these results indicate that MnP turnover in the presence of unsaturated lipids generates reactive lipid oxyradicals that could act as oxidant of other molecules; MnP-mediated lipid peroxidation results in the co-oxidative cleavage of nonphenolic lignin structures, the MnP/lipid peroxidation system may therefore provide C. subvermispora and other LiP-negative fungi with a mechanism to degrade the principal structures of lignin.
Date: June 1, 1997
Partner: UNT Libraries Government Documents Department

Characterization of lignin and Mn peroxidases from Phanerochaete chrysosporium. Progress report

Description: Long-term objectives are to elucidate the role and mechanism of the various isozymes in lignin biodegradation. Work is described on electrochemical studies on lignin and Mn peroxidases. This study was performed to investigate the structural aspects which confer the lignin and Mn peroxidases with their high reactivity. The experimentally determined redox potential of the Fe{sup 3+}/Fe{sup 2+} couple for the lignin peroxidase isozymes H1, H2, H8 and H10 are very similar, near-130 mV. The redox potential for the Mn peroxidase isozymes H3 and H4 are similar to each other ({minus}88 mV and {minus}95 mV, respectively) and are more positive than the lignin peroxidases. The higher redox potential for the Fe{sup 3+}/Fe{sup 2+} couple is consistent with the heme active site of these fungal peroxidases being more electron deficient. To investigate the accessibility of the heme active site to the substrate which is oxidized [veratryl alcohol and Mn (II)], we investigated whether these substrates had any affect on the redox potential of the heme. The E{sub m7} value for lignin and Mn peroxidases are not affected by their respective substrates, veratryl alcohol and Mn (II). These results suggest that substrates do not directly interact with the ferric heme-iron as axial ligands. This is consistent with the present model for peroxidase catalysis. Suicide inhibitor (1) and nmr studies (2) indicate that the heme-iron of horseradish peroxidase (HRP) is not fully accessible to bulky substrates occur at the periphery of the heme.
Date: December 31, 1991
Partner: UNT Libraries Government Documents Department

Enzymatic Upgrading of Heavy Crudes via Partial Oxidation or Conversion of PAHs

Description: The objective of this program was to investigate new enzyme-based technologies for upgrading of heavy oils. Enzymes were selected for screening from those capable of conversion of polyaromatic hydrocarbons (PAHs) reported in the literature. Oxidative reactions of PAHs using hydrogen peroxide as an oxidant with conversion to partially oxidized products were used. The enzymes (lignin peroxidase, cytochrome c) were tested in various organic solvents and found to loose activity in pure organic solvents. A thermodynamic analysis revealed lack of effective interaction between the substrate and enzyme as the cause for low activity. The protein cytochrome c was modified to work in organic media by chemical hydrophobic group attachment. Two different modifications were made: attachment of polyethylene glycol (PEG) and alkyl groups. Alkyl groups, being small could be attached at interior locations within the core of the enzyme and possibly near the active site. Increase in the threshold solvent concentration where maximum enzyme activity occurred indicated potential of this strategy for effective enzyme-substrate interaction. Further improvements in enzyme activity called for other diverse methods due to the unavailability of sufficient chemical modification sites. Genetic techniques were therefore explored for further improvements. These experiments focused on cloning of a gene for the fungal enzyme lignin peroxidase (lip) into yeast Pichia pastoris, which would allow easy manipulation of the gene. However, differences in the fungal and yeast cellular machinery impeded significant expression of the fungal enzyme. Several strategies were explored to allow higher-level expression of the enzyme, which was required for enzyme improvement. The strategies used in this investigation are described in the report. Industrial in-kind support was available throughout the project period. review of the research results was carried out on a regular basis (bimonthly reports and annual meetings) followed by suggestions for improvement in ongoing work and direction for future work. ...
Date: July 1, 2002
Creator: Borole, A.P.; Davison, B.H. & Kuritz, T.
Partner: UNT Libraries Government Documents Department

Regulation of coal polymer degradation by fungi. Eighth quarterly report, [January--March 1996]

Description: Progress is reported on solubilization of low-rank coal by enzyme activity derived from Trametes versicolor or P. chrysosporium. Specifically during the reporting period efforts were directed towards the determining the effect of pH on solubilization of leonardite, the role of laccase in low coal solubilization and metabolism, the decolorization of soluble coal macromolecule by P. chrysosprium and T. versicolor in solid agar gel, and the solubilization of low rank coal in slurry cultures and solid phase reactors.
Date: July 28, 1996
Creator: Irvine, R.L. & Bumpus, J.A.
Partner: UNT Libraries Government Documents Department

Regulation of coal polymer degradation by fungi. Fourth quarterly progress report, May 1995--June 1995

Description: To test the hypothesis that coal (leonardite) Solubilization and the subsequent depolymerization of the solubilized coal macromolecules are distinct events in lignin degrading fungi. In addition to T versicolor, Phanerochaete chrysosporium, another lignin degrading fungus that also has the ability to solubilize coal, will be studied. To test the hypothesis that the processes of coal (leonardite) solubilization and coal macro molecule depolymerization in lignin degrading fungi can be regulated by altering the nutritional status of the microorganism. Coal solubilization is expected to occur in nutrient rich media whereas depolymerization of solubilized coal macromolecules is expected to occur in nutrient limited media. To determine the role of extracellular enzymes (laccases, lignin peroxidases and Mn peroxidases) that are secreted by lignin degrading fungi during coal solubilization or coal macro molecule depolymerization. To assess the role of enzymatically generated oxygen radicals, non-radical active oxygen species, veratryl alcohol radicals and Mn{sup +++} complexes in coal macro molecule depolymerization. To characterize products of coal solubilization and coal macro molecule depolymerization that are formed by T. versicolor and P. chrysosporium and their respective extracellular enzymes. Solubilization products formed using oxalic acid and other metal chelators will also be characterized and compared.
Date: July 24, 1995
Creator: Irvine, R.L.
Partner: UNT Libraries Government Documents Department

The effects of selenium on glutathione peroxidase activity and radioprotection in mammalian cells

Description: The media of representative mammalian cell lines were supplemented with low levels of selenium in the form of sodium selenite in order to investigate the effects of selenium on mammalian cells. Following incubation in 30 nM sodium selenite, these cells were assayed for changes in glutathione peroxidase (GPx) activity. The cells examined included NIH 3T3 mouse fibroblasts, PC12 rat sympathetic precursor cells, SupT-1 human lymphocytes, MCF-7{sup adr} human breast carcinoma cells and AA8 Chinese hamster ovary cells. Selenium supplementation resulted in a marginal increase in GPx activity for the NIH 3T3, MCF-7{sup adr} and Supt-1 cells but stimulated GPx activity approximately 5-fold in PC12 and AA8 cells. AA8 cells were selected to evaluate whether selenium supplementation was radioprotective against {sup 60}cobalt gamma irradiation. Protection against radiation-induced mutation was measured by evaluating mutation frequency at the hprt locus. In this assay, preincubation of AA8 CHO cells significantly protected these cells from exposure to 8 Gy.
Date: September 5, 1995
Creator: Diamond, A.M.; Murray, J.L.; Dale, P.; Tritz, R. & Grdina, D.J.
Partner: UNT Libraries Government Documents Department

Regulation of coal degradation by fungi. Third quarterly report, January 1995--March 1995

Description: Progress is reported on the solubilization and depolymerization of coal by fungi. It is postulated the the solubilization and depolymerization are separate events. Other objectives include the determination of the role that laccases and peroxidases exert, to access the role of oxygen radicals and oxygen species, and to characterize the solubilization products formed.
Date: April 24, 1995
Creator: Irvine, R.L. & Bumpus, J.A.
Partner: UNT Libraries Government Documents Department

Unravelling lignin formation and structure. Final report, April 1, 1988--March 31, 1991

Description: During this study, we established that the Fagaceae exclusively accumulate Z-monolignois/glucosides, and not the E-isomers. Evidence for the presence of a novel E{yields}Z isomerse has been obtained. Our pioneering work in lignin biosynthesis and structure in situ has also progressed smoothly. We established the bonding environments of a woody angiosperm, Leucanea leucocephala, as well as wheat (T. aestivum) and tobacco (N. tabacum). A cell culture system from Pinus taeda was developed which seems ideal for investigating the early stages of lignification. These cultures excrete peroxidase isozymes, considered to be specifically involved in lignin deposition. We also studied the effect of the putative lignin-degrading enzyme, lignin peroxidase, on monolignols and dehydropolymerisates therefrom. In all cases, polymerization was observed, and not degradation; these polymers are identical to that obtained with horseradish peroxidases/H{sub 2}O{sub 2}. It seems inconceivable that these enzymes can be considered as being primarily responsible for lignin biodegradation.
Date: December 31, 1991
Creator: Lewis, N. G.
Partner: UNT Libraries Government Documents Department

Enzymantic Conversion of Coal to Liquid Fuels

Description: The work in this project focused on the conversion of bituminous coal to liquid hydrocarbons. The major steps in this process include mechanical pretreatment, chemical pretreatment, and finally solubilization and conversion of coal to liquid hydrocarbons. Two different types of mechanical pretreatment were considered for the process: hammer mill grinding and jet mill grinding. After research and experimentation, it was decided to use jet mill grinding, which allows for coal to be ground down to particle sizes of 5 {mu}m or less. A Fluid Energy Model 0101 JET-O-MIZER-630 size reduction mill was purchased for this purpose. This machine was completed and final testing was performed on the machine at the Fluid Energy facilities in Telford, PA. The test results from the machine show that it can indeed perform to the required specifications and is able to grind coal down to a mean particle size that is ideal for experimentation. Solubilization and conversion experiments were performed on various pretreated coal samples using 3 different approaches: (1) enzymatic - using extracellular Laccase and Manganese Peroxidase (MnP), (2) chemical - using Ammonium Tartrate and Manganese Peroxidase, and (3) enzymatic - using the live organisms Phanerochaete chrysosporium. Spectral analysis was used to determine how effective each of these methods were in decomposing bituminous coal. After analysis of the results and other considerations, such as cost and environmental impacts, it was determined that the enzymatic approaches, as opposed to the chemical approaches using chelators, were more effective in decomposing coal. The results from the laccase/MnP experiments and Phanerochaete chrysosporium experiments are presented and compared in this final report. Spectra from both enzymatic methods show absorption peaks in the 240nm to 300nm region. These peaks correspond to aromatic intermediates formed when breaking down the coal structure. The peaks then decrease in absorbance over time, corresponding to ...
Date: January 31, 2011
Creator: Troiano, Richard
Partner: UNT Libraries Government Documents Department

Altered phenotypes in plants transformed with chimeric tobacco peroxidase genes

Description: Peroxidases have been implicated in a variety of secondary metabolic reactions including lignification, cross-linking of cell wall polysaccharides, oxidation of indole-3-acetic acid, regulation of cell elongation, wound-healing, phenol oxidation, and pathogen defense. However, due to the many different isoenzymes and even more potential substrates, it has proven difficult to verify actual physiological roles for peroxidase. We are studying the molecular biology of the tobacco peroxidase genes, and have utilized genetic engineering techniques to produce transgenic plants which differ only in their expression of an individual peroxidase isoenzyme. Many of the in planta functions for any individual isoenzyme may be predicted through the morphological and physiological analysis of transformed plants.
Date: January 1, 1990
Creator: Lagrimini, L.M.
Partner: UNT Libraries Government Documents Department

Characterization of lignin and Mn peroxidases from Phanerochaete chrysosporium

Description: Long-term objectives are to elucidate the role and mechanism of the various isozymes in lignin biodegradation. Work is described on electrochemical studies on lignin and Mn peroxidases. This study was performed to investigate the structural aspects which confer the lignin and Mn peroxidases with their high reactivity. The experimentally determined redox potential of the Fe{sup 3+}/Fe{sup 2+} couple for the lignin peroxidase isozymes H1, H2, H8 and H10 are very similar, near-130 mV. The redox potential for the Mn peroxidase isozymes H3 and H4 are similar to each other ({minus}88 mV and {minus}95 mV, respectively) and are more positive than the lignin peroxidases. The higher redox potential for the Fe{sup 3+}/Fe{sup 2+} couple is consistent with the heme active site of these fungal peroxidases being more electron deficient. To investigate the accessibility of the heme active site to the substrate which is oxidized (veratryl alcohol and Mn (II)), we investigated whether these substrates had any affect on the redox potential of the heme. The E{sub m7} value for lignin and Mn peroxidases are not affected by their respective substrates, veratryl alcohol and Mn (II). These results suggest that substrates do not directly interact with the ferric heme-iron as axial ligands. This is consistent with the present model for peroxidase catalysis. Suicide inhibitor (1) and nmr studies (2) indicate that the heme-iron of horseradish peroxidase (HRP) is not fully accessible to bulky substrates occur at the periphery of the heme.
Date: January 1, 1991
Partner: UNT Libraries Government Documents Department

The molecular characterization of the lignin-forming peroxidase

Description: This laboratory is committed to understanding the function of plant peroxidases via a multi-disciplinary approach. We have chosen the lignin-forming peroxidase from tobacco as the first isoenzyme to be subjected to this comprehensive approach. The goals which were set out upon the initiation of this project were as follows: (1) utilize a cDNA clone to the tobacco anionic peroxidase to generate transgenic plants which either over-produced this isoenzyme or specifically under-produced this isoenzyme via antisense RNA, (2) describe any phenotypic changes resulting from altered peroxidase expression, (3) perform morphological, physiological, and biochemical analysis of the above mentioned plants to help in determining the in planta function for this enzyme, and (4) clone and characterize the gene for the tobacco anionic peroxidase. A summary of progress thus far which includes both published and unpublished work will be presented in three sections: generation and characterization of transgenic plants, description of phenotypes, and biochemical and physiological analysis of peroxidase function, and cloning and characterization of the tobacco anionic peroxidase gene.
Date: January 1, 1992
Creator: Lagrimini, L.M.
Partner: UNT Libraries Government Documents Department