Pulp and Paper Research Institute of Canada, Pointe Claire, Quebec.
Abstract
Many ligninolytic basidiomycete fungi have been shown to secrete a group of peroxidase isozymes whose sole function appears to be the peroxide-dependent oxidation of manganous [Mn(II)] to manganic [Mn(III)] ions. Manganic chelates and these Mn peroxidases have been implicated as central to the degradation of various natural and synthetic lignins and lignin-containing effluents by white rot (ligninolytic) fungi. Another group of enzymes, the laccases, are commonly secreted by wood-rotting fungi, but are generally regarded as being able to oxidize (and usually polymerize) only phenolic substrates. In this report it is shown that in the presence of appropriate oxidizable phenolic accessory substances or primary substrates, a variety of laccases and peroxidases catalyzing one-electron oxidations can also produce Mn(III) chelates from Mn(II).
PMID: 1622216 [PubMed – indexed for MEDLINE]PMCID: PMC195631
Department of Surgery II, Faculty of Medicine, Kyushu University Fukuoka, Japan.
Abstract
We evaluated the effects of chemotherapy given postoperatively with and without immunomodulators on the survival of patients who had undergone resection for gastric cancer. We conducted a retrospective survey of data on 963 Japanese patients treated at our department of surgery between 1965 and 1987. Data related to the duration of postoperative survival were calculated for those who received chemotherapy, i.e. an individualized combination of various agents given with or without the immunomodulators PSK, a protein extract of the fungus Coriolus versicolor, and/or OK-432, a preparation of an attenuated strain of Streptococcus (immunochemotherapy). Postoperative immunochemotherapy was more often prescribed for patients with advanced disease. The survival of patients who received immunochemotherapy was shorter than that of patients who received only chemotherapy. In a subgroup of patients adjusted for disease stage, the survival of those on chemotherapy versus immunochemotherapy did not differ significantly at any stage. For optimal results, a protocol for postoperative immunochemotherapy needs to be designed and investigated prospectively and according to the stage of gastric cancer. The stage III gastric cancers seem amenable to a favorable response.
Central Research Laboratories, Mercian Co., Fujisawa, Japan.
Abstract
Penicillin X methyl ester was transformed into three types of dimer by laccase from Coriolus versicolor. The dimers are considered to be formed by free-radical addition of phenoxy radicals produced by laccase. The enzyme reaction with the ester as substrate was more suitable for forming dimers than that with the sodium salt as substrate. Penicillin X pivaloyloxymethyl ester was also transformed into a dimer, which had antibacterial activity in the presence of esterase.
Pulp and Paper Research Institute of Canada, 570 St. John’s Boulevard, Pointe Claire, Quebec H9R 3J9, Canada.
Abstract
Previous work has shown that Trametes (Coriolus) versicolor bleaches kraft pulp brownstock with the concomitant release of methanol. In this work, the fungus is shown to produce both laccase and manganese peroxidase (MnP) but not lignin peroxidase during pulp bleaching. MnP production was enhanced by the presence of pulp and/or Mn(II) ions. The maximum level of secreted MnP was coincident with the maximum rate of fungal bleaching. Culture filtrates isolated from bleaching cultures produced Mn(II)- and hydrogen peroxide-dependent pulp demethylation and delignification. Laccase and MnP were separated by ion-exchange chromatography. Purified MnP alone produced most of the demethylation and delignification exhibited by the culture filtrates. On the basis of the methanol released and the total and phenolic methoxyl contents of the pulp, it appears that MnP shows a preference for the oxidation of phenolic lignin substructures. The extensive increase in brightness observed in the fungus-treated pulp was not found with MnP alone. Therefore, either the MnP effect must be optimized or other enzymes or compounds from the fungus are also required for brightening.
The ability of 10 dikaryotic and 20 monokaryotic strains of Trametes (Coriolus) versicolor to bleach and delignify hardwood and softwood kraft pulps was assessed. A dikaryon (52P) and two of its mating-compatible monokaryons (52J and 52D) derived via protoplasting were compared. All three regularly bleached hardwood kraft pulp more than 20 brightness points (International Standards Organization) in 5 days and softwood kraft pulp the same amount in 12 days. Delignification (kappa number reduction) by the dikaryon and the monokaryons was similar, but the growth of the monokaryons was slower. Insoluble dark pigments were commonly found in the mycelium, medium, and pulp of the dikaryon only. Laccase and manganese peroxidase (MnP) but not lignin peroxidase activities were secreted during bleaching by all three strains. Their laccase and MnP isozyme patterns were compared on native gels. No segregation of isozyme bands between the monokaryons was found. Hardwood kraft pulp appeared to adsorb several laccase isozyme bands. One MnP isozyme (pI, 3.2) was secreted in the presence of pulp by all three strains, but a second (pI, 4.9) was produced only by 52P. A lower level of soluble MnP activity in one monokaryon (52D) was associated with reduced bleaching ability and a lower level of methanol production. Since monokaryon 52J bleached pulp better than its parent dikaryon 52P, especially per unit of biomass, this genetically simpler monokaryon will be the preferred subject for further genetic manipulation and improvement of fungal pulp biological bleaching.
Department of Forest Products, Faculty of Agriculture, Kyushu University, Fukuoka 812, Japan.
Abstract
When 4-methylguaiacol (MeG), a phenolic lignin model compound, was added to a culture that was inoculated with Coriolus versicolor, it was bioconverted into 2-methoxy-4-methylphenyl beta-d-xyloside (MeG-Xyl). The phenolic hydroxyl group of vanillyl alcohol was much more extensively xylosylated than the alcoholic hydroxyl group. When a mixture of MeG and commercial UDP-xylose was incubated with cell extracts of mycelia, transformation of UDP-xylose into MeG-Xyl was observed. This result suggested that UDP-xylosyltransferase was involved in the xylosylation of phenolic hydroxyl groups of lignin model compounds.
Department of Biochemistry, First Medical College of PLA, Guang Zhou, P.R.C.
Abstract
Using a luminol-dependent, chemiluminescence assay we found tert-butylhydroperoxide to be a strong inhibitor of the respiratory burst of mouse peritoneal macrophages. However, the inhibition of respiratory burst induced by tert-butylhydroperoxide could be prevented after the interperitoneal injection of polysaccharide from Coriolus versicolor (PSK). Further investigation showed that glutathione peroxidase activity was markedly elevated in PSK-treated macrophages. After incubation with tert-butylhydroperoxide, higher activity of glutathione peroxidase was maintained in PSK-treated macrophages. These results suggest that the immunological function of macrophages is related to the activity of glutathione peroxidase. The non-specific immunopolysaccharide might protect macrophages from the damage induced by reactive oxygen species by enhancing antioxidative capacity.
First Department of Biochemistry, School of Medicine, Showa University, Tokyo, Japan.
Abstract
PSK (Krestin), a protein-bound polysaccharide extracted from Coriolus versicolor, stimulated the production of interleukin-1 (IL-1) by human peripheral blood mononuclear cells more efficiently than the production of tumor necrosis factor (TNF). More IL-1 alpha was accumulated in the cells than in the medium fraction, whereas IL-1 beta was distributed evenly into both fractions. PSK stimulated the production of adherent mononuclear cells, in which significantly higher amounts of IL-1 alpha/IL-1 beta were accumulated per cell than in nonadherent cells. Although IL-1 alpha mRNA synthesis (assessed by Reverse Transcriptase-Polymerase Chain Reaction) was slightly enhanced, IL-1 beta mRNA synthesis was not significantly changed by PSK treatment. This suggests that PSK might increase the efficiency of IL-1 mRNA translation or the posttranslational processing of IL-1 protein. Despite potent cytokine-inducing activity, lipopolysaccharide (LPS) did not significantly stimulate the production of adherent cells. These data suggest that PSK and LPS might stimulate mononuclear cells by different mechanisms.
PSK, a protein-bound polysaccharide preparation obtained from cultured mycelia of the CM-101 strain of Coriolus versicolor belonging to basidiomycetes, is a biological response modifier capable of exhibiting diverse biological activities. This agent has been used clinically for the treatment of postoperative cancer patients in Japan by oral use. In this paper, chemopreventive aspects of PSK were reviewed. Oral administration of PSK reduced the incidence of tumor and/or prolonged the survival period in the following chemical carcinogen-induced, radiation-induced, and spontaneously developed animal cancer models: rat gastrointestinal cancer induced by 1,2-dimethylhydrazine; rat hepatoma by 3′-methyl-dimethylaminobenzene; mouse thymic lymphoma by whole-body irradiation; mouse spontaneous mammary tumor; and so on. PSK did not interact and/or inhibit drug-metabolizing enzymes and had no effect on the Ames test. On the other hand, this agent scavenged active oxygen through the induction of manganese superoxide dismutase, prevented the increase in frequency of anticancer agent-induced sister chromatid exchange, and suppressed fetal deformation induced by transplacental injection of teratogen, suggesting an effect on the initiation or promotion process of carcinogenesis. Also, PSK regulated cytokine production and enhanced the antitumor activity of effector cells such as killer T-cells and natural killer cells, suggesting an effect on the growth process after the development of malignant cells. Thus, this agent seems to act at multiple steps during carcinogenesis rather than a particular step. The main mechanism may be an antiteratogenic effect attributed to radical trapping, preventive effects against chromosome injury, and immunomodulative effects attributed to the modulation of cytokine production and effector cell function.(ABSTRACT TRUNCATED AT 250 WORDS)