Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LIGNIN”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,297 records · Page 72Linked to original sources
PubMed1982

Enzymic synthesis of lignin precursors. Purification and properties of UDP glucose: coniferyl-alcohol glucosyltransferase from cambial sap of spruce (Picea abies L.).

UDPglucose:coniferyl-alcohol glucosyltransferase was isolated from cambial sap of spruce (Picea abies). An apparently homogeneous enzyme was obtained by a seven-step procedure including dye-ligand chromatography. The enzyme has an Mr of about 50 000 and consists of one polypeptide chain. Transferase activity is not influenced by metal ions. The enzyme shows a pronounced substrate specificity towards UDPglucose and coniferyl alcohol with Km values of respectively 220 microM and 250 microM. The only reaction product is coniferin (coniferyl alcohol 7-O-beta-D-glucopyranoside). No formation of 'isoconiferin' (coniferyl alcohol 1-O-beta-D-glucoside) was detected. The reversibility of the reaction was proved by formation of [3H]UDPglucose from [3H]UDP and coniferin in the presence of the transferase. The products UDP and coniferin inhibit the reaction noncompetitively. Product inhibition patterns are consistent with a mono-iso-ordered bibi mechanism involving two isomeric enzyme forms.

Cinnamates↗
PubMed1982

Isolation and Complementation Studies of Auxotrophic Mutants of the Lignin-Degrading Basidiomycete Phanerochaete chrysosporium.

A variety of auxotrophic strains of Phanerochaete chrysosporium were isolated after treatment of conidia with UV and X rays. Complementation studies with these strains demonstrated heterokaryotic mycelia and conidia in this organism. Nuclear staining also showed that conidia can be mono-, di-, or multinucleate. Complementation tests allowed the separation of each auxotrophic class with the same phenotype into complementation groups.

Journal Article↗
PubMed1985

Arylglycerol-gamma-Formyl Ester as an Aromatic Ring Cleavage Product of Nonphenolic beta-O-4 Lignin Substructure Model Compounds Degraded by Coriolus versicolor.

4-Ethoxy-3-methoxyphenylglycerol-gamma-formyl ester (compound IV) was identified as a degradation product of both 4-ethoxy-3-methoxyphenylglycerol-beta-syringaldehyde ether (compound I) and 4-ethoxy-3-methoxyphenylglycerol-beta-2,6-dimethoxyphenyl ether (compound II) by a ligninolytic culture of Coriolus versicolor. An isotopic experiment with a C-labeled compound (compound II') indicated that the formyl group of compound IV was derived from the beta-phenoxyl group of beta-O-4 dimer as an aromatic ring cleavage fragment. However, compound IV was not formed from 4-ethoxy-3-methoxyphenylglycerol-beta-guaiacyl ether (compound III). gamma-Formyl arylglycerol (compound IV) could be a precursor of 4-ethoxy-3-methoxyphenylglycerol (compound VI), because 3-(4-ethoxy-3-methoxyphenyl)-1-formyloxy propane (compound VII) was cleaved to give 3-(4-ethoxy-3-methoxyphenyl)-1-propanol (compound VIII) by C. versicolor. 4-Ethoxy-3-methoxyphenylglycerol-beta,gamma-cyclic carbonate (compound V), previously found as a degradation product of compound III by Phanerochaete chrysosporium (T. Umezawa, and T. Higuchi, FEBS Lett., 25:123-126, 1985), was also identified from the cultures with compound I, II, and III and degraded to give the arylglycerol (compound VI). An isotopic experiment with C-labeled compounds II' and III' indicated that the carbonate carbon of compound V was derived from the beta-phenoxyl groups of beta-O-4 substructure.

Journal Article↗
PubMed1989

Transformation by Complementation of an Adenine Auxotroph of the Lignin-Degrading Basidiomycete Phanerochaete chrysosporium.

Swollen basidiospores of an adenine auxotroph of Phanerochaete chrysosporium were protoplasted with Novozyme 234 and transformed to prototrophy by using a plasmid containing the gene for an adenine biosynthetic enzyme from Schizophyllum commune. Transformation frequencies of 100 transformants per mug of DNA were obtained. Southern blot analysis of DNA extracted from transformants demonstrated that plasmid DNA was integrated into the chromosomal DNA in multiple tandem copies. Analysis of conidia and basidiospores from transformants demonstrated that the transforming character was mitotically and meiotically stable on both selective and nonselective media. Genetic crosses between double mutants transformed for adenine prototrophy and other auxotrophic strains yielded Ade progeny, which indicated that integration occurred at a site(s) other than the resident adenine biosynthetic gene.

Journal Article↗
PubMed1990

Oxidation of Lignin-Related Aromatic Alcohols by Cell Suspensions of Methylosinus trichosporium.

Cell suspensions of Methylosinus trichosporium oxidized the aromatic alcohols benzyl alcohol, vanillyl alcohol, and veratryl alcohol to the corresponding aldehydes, and with the exception of vanillyl alcohol, the aldehydes were further oxidized to the corresponding aromatic acids. No other transformation was observed, and the methoxyl moieties attached to the aromatic nucleus remained intact. More than 70% of the alcohol oxidized could be accounted for by aldehyde and/or acid. Investigation of the inhibitor kinetics of EDTA or p-nitrophenylhydrazine (specific for NAD-independent methanol dehydrogenase in methylotrophs) on aromatic alcohol oxidation revealed noncompetitive inhibition in which the V(max) was decreased but the K(m) remained unchanged. The pattern of inhibition of aromatic alcohol oxidation matched that of methanol oxidation, and the K(m) values for all of the substrates were similar (12 to 16 mM). The results indicate that the initial step in the oxidation of aromatic alcohols was similar to that for methanol, and because oxidation was incomplete (i.e., only the corresponding aldehyde or acid was produced), there may be some biotechnological advantages in using whole cells of methylotrophs to facilitate aromatic biotransformations.

Journal Article↗
PubMed1991

Genetic Mapping in the Lignin-Degrading Basidiomycete Phanerochaete chrysosporium.

A method of meiotic segregation analysis based on recombinant selection in the homothallic basidiomycete Phanerochaete chrysosporium was developed. Using this method, we were able to reveal linkage relationships and to estimate recombination frequencies between seven mutations to auxotrophy. We detected two linkage groups, the first containing four and the second three of the seven mapped mutations.

Journal Article↗
PubMed1997

Reactivities of various mediators and laccases with kraft pulp and lignin model compounds.

Laccase-catalyzed oxygen delignification of kraft pulp offers some potential as a replacement for conventional chemical bleaching and has the advantage of requiring much lower pressure and temperature. However, chemical mediators are required for effective delignification by laccase, and their price is currently too high at the dosages required. To date, most studies have employed laccase from Trametes versicolor. We have found significant differences in reactivity between laccases from different fungi when they are tested for pulp delignification in the presence of the mediators 2,2(prm1)-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT). A more detailed study of T. versicolor laccase with ABTS and HBT showed that HBT gave the most extensive delignification over 2 h but deactivated the enzyme, and therefore a higher enzyme dosage was required. Other mediators, including 1-nitroso-2-naphthol-3,6-disulfonic acid, 4-hydroxy-3-nitroso-1-naphthalenesulfonic acid, promazine, chlorpromazine, and Remazol brilliant blue, were also tested for their ability to delignify kraft pulp. Studies with dimeric model compounds indicated that the mechanisms of oxidation by ABTS and HBT are different. In addition, oxygen uptake by laccase is much slower with HBT than with ABTS. It is proposed that the dication of ABTS and the 1-oxide radical of HBT, with redox potentials in the 0.8- to 0.9-V range, are required for pulp delignification.

Journal Article↗