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Biomedical subjects

K E Eriksson

Publications and source records attributed to K E Eriksson.

At least 55 records · Page 3Linked to original sources
PubMed1982

Purification and partial characterization of two acidic proteases from the white-rot fungus Sporotrichum pulverulentum.

Two acidic proteases from the white-rot fungus Sporotrichum pulverulentum have been purified and partially characterized. The enzymes were purified in four steps, protease I 152-fold and protease II 127-fold. The purity of the enzymes was investigated by analytical isoelectric focusing and by dodecylsulfate/polyacrylamide gel electrophoresis. The isoelectric points of protease I and protease II were at pH 4.7 and 4.2 respectively. The molecular weights were 28,000 and 26,000 and the pH optima 5.0 and 5.2. Both enzymes were inhibited by heavy metal ions such as Ag+, Hg2+ and to some extent also by Cu2+. Partial inhibition was also observed with EDTA and alpha, alpha'-dipyridyl. The specificities of protease I and II were investigated using human fibrinopeptide A as substrate. Protease I splits off the arginine in the C-terminal position, while protease II splits at the carboxyl side of both Phe-8 and Leu-9 in fibrinopeptide A. A physiological effect of the two proteases has also been demonstrated. Thus, if a culture solution from S. pulverulentum grown on cellulose was treated with the individual proteases or a mixture of the enzymes a considerable increase in endo-1,4-beta-glucanase activity was obtained. It may be that the endo-glucanases are produced in a zymogenic form and activated by the proteases. However, other explanations for the phenomenon are also possible.

Cellulase↗
PubMed1981

Mutagenic effects of effluents from chlorine bleaching of pulp.

Effluents from the bleaching of kraft pulp were tested for mutagenicity. Samples from different mills in which softwood kraft pulp is bleached in a conventional sequence of stages were spot-tested with the Escherichia coli pol A-/pol A+ system. All samples were nontoxic and therefore no difference could be noted between the repair-proficient and the repair-deficient strain. Also no toxic mutagenic effects were seen in spot tests with Salmonella. In a quantitative test with Salmonella, using the plate incorporation assay, effluents from the chlorination (C) stage induced point mutations of the base-substitution type. No frameshift mutations were noted. In the presence of a metabolizing system the direct mutagenic effect was reduced. This reduction was essentially NADPH-independent. Tests on effluents concentrated by freeze-drying indicated, in addition to the base-substitution effect of the C-stage effluent, the presence of frameshift mutagen(s) in this effluent and a base-substitution effect of the hypochlorite stage effluent. Fractionation of the C-stage effluent showed that the mutagenic components are of low molecular weight, extractable with diethyl ether, and sensitive to alkali treatment. Most of the mutagenicity is found in the neutral ether fraction. Induction of 6-thioguanine-resistant mutants in Chinese hamster V79 cells confirmed the mutagenic properties of the C-stage effluent.

Animals↗
PubMed1978

Cellobiose oxidase, purification and partial characterization of a hemoprotein from Sporotrichum pulverulentum.

An extracellular enzyme which utilizes molecular oxygen to oxidize cellodextrins to the corresponding aldonic acids has been isolated from culture filtrates of the white-rot fungus Sporotrichum pulverulentum. This enzyme, tentatively named cellobiose oxidase, has been highly purified by classical techniques and has been demonstrated to be a glycoprotein with a molecular weight of approximately 93000. Ultraviolet spectra of the enzyme in the presence and absence of substrate are characteristic of a hemoprotein. Acidic hydrolyses of the enzyme followed by a spectrofluorimetric investigation of the hydrolysate has demonstrated the presence of approximately one flavin component per enzyme molecule. The possible role of this complex enzyme in cellulose degradation is discussed.

Carbohydrate Dehydrogenases↗
PubMed1975

Extracellular enzyme system utilized by the fungus Sporotrichum pulverulentum (Chrysosporium lignorum) for the breakdown of cullulose. Functional characterization of five endo-1,4-beta-glucanases and one exo-1,4-beta-glucanase.

A strong synergistic response was observed between the five endo-1,4-beta-glucanases and the exo-1,4-beta-glucanase obtained from culture solutions of the rot fungus Sporotrichum pulverulentum (formerly called Chrysosporium lignorum), when these enzymes were allowed to degrade de-waxed cotton and Avicel. No synergism was observed if Walseth cellulose, an acid-swollen cullulose, was used. If de-waxed cotton was pretreated with endo-1,4-beta-glucanases, the exo-1,4-beta-glucanase enzyme released much more degradation products than from an untreated cotton...

Cellulase↗
PubMed1975

Extracellular enzyme system utilized by the fungus Sporotrichum pulverulentum (Chrysosporium lignorum) for the breakdown of cellulose. 1. Separation, purification and physico-chemical characterization of five endo-1,4-beta-glucanases.

Five endo-1,4-beta-glucanases (EC 3.2.1.4) have been separated from culture solutions OF THE ROT FUNGUS Sporotrichum pulverulentum (formerly called Chrysosporium lignorum) grown on powder cellulose as the sole carbon source. They have been extensively purified and characterized with regard to some physicochemical properties. The purifications have been carried out on a quantitative basis, the purity of the enzymes being tested in several ways. After purification they all showed one single protein band in analytical polyacrylamide electrophoresis, on dodecyl-sulphate gels and in analytical isoelectric focusing on flat-bed polyacrylamide gels. One exo-1,4-beta-glucanase has also been identified in the culture solution and separated from the endo-1,4-beta-glucanases. From the data obtained during the quantitative purification it has been possible to calculate that the ratio of activity between the five endoglucanases T1, T2a, T2b, T3a, and T3b in the culture solutions is 4:1:1:1:1. It has also been calculated that the weight ratio endoglucanase protein to exoglucanase protein is approximately 1:1. Flat-bed isoelectric focusing has been used for the identification of the individual endoglucanases and a new zymogram technique, useful for studies of carbohydrases in general, has been developed. The molecular weights, determined by ultracentrifugation, and calculated on the basis of a knowledge of the amino acid composition and carbohydrate content vary between 28200 and 37500. Small but significant differences in the amino acid compositions of the different endoglucanases have been found. The carbohydrate content varies between 0 and 10.5%, all but one of the enzymes being glycoproteins. For two of these the exact carbohydrate composition has been determined. Enzyme T1 contains 2 glucose and 19 mannose units per enzyme molecule while enzyme T2b contains 5 mannose, 7 galactose, 1 glucose and 1 arabinose unit per molecule.

Amino Acids↗
PubMed1975

Extracellular enzyme system utilized by the fungus Sporotrichum pulverulentum (Chrysosporium lignorum) for the breakdown of cellulose. 2. Activities of the five endo-1,4-beta-glucanases towards carboxymethylcellulose.

A complementary discussion is given of an earlier presented theory for viscometric determination of enzymic activity towards polymer substrates. Five different, purified endo-1,4-beta-glucanases from the fungus Sporotrichum pulverulentum have been characterised with respect to their molecular activities(Am) and Michaelis-Menten constants (Km). The errors in the Am and Km values are discussed. The Am value seems to be more valuable as a distinguishing parameter than the Km value.

Carboxymethylcellulose Sodium↗
PubMed1975

Extracellular enzyme system utilized by the fungus Sporotrichum pulverulentum (Chrysosporium lignorum) for the breakdown of cellulose. 3. Purification and physico-chemical characterization of an exo-1,4-beta-glucanase.

An exo-1,4-beta-glucanase from culture solution of the rot fungus Sporotrichum pulverulentum (formerly called Chrysosporium lignorum) grown on powder cellulose as the sole carbon source has been extensively purified and characterized with respect to some physico-chemical properties. The purification has been carried out in a five-step procedure comprising chromatography on DEAE-Sephadex, gel filtration on polyacrylamide P-150, activation on a Dowex 2-X8 anion exchanger, chromatography on Concanavalin A-Sepharose and chromatography on SP-Sephadex. The purified enzyme was found to be pure and homogeneous by analytical polyacrylamide electrophoresis, by electrophoresis on dodecylsulphate gels and by analytical polyacrylamide electrophoresis, by electrophoresis on dodecylsulphate gels and by analytical isoelectric focusing. A single symmetrical peak was obtained with the free zone electrophoresis method. The purification factor is about 15 and the yield of exo-1,4-beta-glucanase activity 7%. After purification, the enzyme showed no viscosity-decreasing activity towards carboxymethyl-cellulose solutions. The exo-1,4-beta-glucanase was isoelectric at pH 4.3 (4 degrees C). A molecular weight of 48600 was calculated on the basis of a knowledge of the partial specific volume, ultracentrifugation data and the amino acid composition. The enzyme contained no carbohydrate.

Amino Acids↗
PubMed1975

Purification and properties of cellobiose: quinone oxidoreductase from Sporotrichum pulverulentum.

Cellobiose: quinone oxidoreductase was purified by ammonium sulfate precipitation, SP-Sephadex C-50 chromatography, and hydroxylapatite column chromatography. The purified enzyme is homogeneous by ultracentrifugal and SDS-gel electrophoretic analyses. The enzyme is a flavoprotein with FAD as the prosthetic group and produces cellobiono-delta-lactone as the product of cellobiose oxidation. Cellopentaose is also oxidized but no oxidation of cellulose could be detected. The enzyme oxidizes lactose and 4-beta-glucosylmannose but not 4-beta-mannosylglucose which implicates the C-2-hydroxyl of the non-reducing end of the disaccharide as important for substrate specificity.

Alcohol Oxidoreductases↗
PubMed1974

Induction of Neurospora crassa laccase with protein synthesis inhibitors.

Rapidly growing Neurospora crassa does not produce laccase (p-diphenol:oxygen oxidoreductase; EC 1.10.3.2). Low concentrations of cycloheximide induce the production of this enzyme, most of which is secreted into the media. In general, limited inhibition of protein synthesis seems to derepress laccase synthesis since actinomycin D and, to a limited extent, puromycin also induce laccase production. Similarities in the conditions of laccase and tyrosinase induction, plus investigations with two tyrosinase regulatory mutants, suggest that the production of these two phenol oxidases is controlled by the same mechanism. As shown by polyacrylamide gel electrophoresis, most of the 10 to 12 proteins normally present in the medium virtually disappear during cycloheximide treatment. In contrast, the amounts of two proteins that are present in only very minor quantities, if at all, in normal culture filtrates increase dramatically. One of these proteins co-migrates with laccase, whereas the other has not been identified.

Benzene Derivatives↗
PubMed1974

Purification and properties of Neurospora crassa laccase.

Extracellular Neurospora laccase (p-diphenol:oxygen oxidoreductase; EC 1.10.3.2) has been purified to apparent homogeneity by classical purification techniques. The enzyme, which consists of mainly one form, has a molecular weight of 64,800 and contains 11% carbohydrate. The ultraviolet, visible, and electron paramagnetic resonance spectra indicate that both type I and type II copper are present, as described for the Polyporus versicolor enzyme. With the exception of phloroglucinol, only para- and ortho-diphenols serve as effective substrates for the enzyme. Like the extracellular form, intracellular laccase is a glycoprotein as shown by its ability to bind to Concanavalin A Sepharose. Other studies, including gel filtration and ion-exchange chromatography, revealed no differences between the intracellular and extracellular enzymes, suggesting that intracellular laccase is destined for excretion by the cell.

Amino Acids↗