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1. A β-glucosidase (cellobiase) has been isolated from a commercial cellulase preparation derived from culture filtrates of the fungus Trichoderma viride. 2. The crude material was pre-fractionated by chromatography on Bio-Gel P-10 and by DEAE-Sephadex chromatography as previously described [1]. Further fractionation methods utilized in the present paper included ammonium sulfate precipitation. SE-Sephadex chromatography, isoelectric focusing, and chromatography on Bio-Gel P-60. 3. A yield of 53 mg enzyme was obtained per 100 g commercial cellulase. The specific activity of the purified enzyme represented an approximately 60-fold increase from that of the commercial product. 4. The isolated enzyme was homogeneous in polyacrylamide gel electrophoresis at pH 8.0 by isoelectric focusing in a polyacrylamide gel and also in free zone electrophoresis. 5. No enzyme activity towards Avicel (mieroerystalline cellulose) or towards carboxymethylcellulose could be detected in the purified material under the assay conditions used. 6. A molecular weight of 47 000 was determined for the enzyme by dodecylsulfate-polyacrylamide gel electrophoresis. The same molecular weight value was obtained by chromatography of the native enzyme on Bio-Gel P-100 and also by chromatography of the reduced and alkylated enzyme on Sepharose 6B in 6 M guanidine-HCl. 7. The amino-acid analysis showed that the enzyme was rich in aromatic (9.5%) and acidic (19.0%) amino acids. The half-cystine content was 6 residues per molecule indicating 3 disulfide bridges, since no free sulfhydryl group was detectable. The purified enzyme contained no carbohydrate (as hexose). 8. The enzyme was isoelectric at pH 5.74 (10 °C) and the electrophoretic mobility was determined to be 1.49 × 10-5 cm² s-1 V-1 at pH 8.0. 9. The Km-values for the enzyme towards the substrates p-nitrophenyl-β-D-glucoside, cellobiose, and cellotetraose were found to be 0.28, 1.5, and 0.35 mM, respectively. [ABSTRACT FROM AUTHOR]

The removal of stratum corneum in vivo by cellophane tape stripping is a traumatic procedure, as evidenced by considerable acute erythema. This may render the skin less suitable for subsequent experimentation. Hydration of the stratum corneum by occlusion under a water-saturated patch for 24 hours prior to stripping greatly facilitates the procedure. Removal is accomplished with less force, and with about ⅓ the number of strippings ordinarily required. Also, there is usually less erythema than after stripping of dry skin. Why hydration should loosen stratum corneum cells from each other is not known. [ABSTRACT FROM AUTHOR]

D-Altronate: NAD-oxidoreductase of Escherichia coli K12 has been purified. The purification consists of four steps: nucleic acids precipitation with protamine sulfate; ammonium sulfate precipitation; ion exchange chromatography on DEAE-cellulose and Sephadex G-150 gel filtration. The overall procedure results in a 53-fold purification with a yield of 60%. Altronate oxidoreductase is an inducible enzyme: galacturonate, tagaturonate, glucuronate and fructuronate are good inducers. The activity remains stable at 4 °C or at — 20 °C for several months. Optimal activity is obtained at pH 6.3 for tagaturonate reduction, and at pH 8.9 for altronate oxidation. Altronate oxidoreductase does not require any cofactor, except NADH. The apparent Michaelis constants have been determined: for tagaturonate, the Km is 350 μM; for NADH, 60 μM; for altronate, 90 μM, and for NAD+, 110 μM. Moreover, altronate oxidoreductase is active with NADPH as coenzyme and the apparent Km value for NADPH is 400 μM. Other carbohydrates tested are unsuitable as substrates. Many other carbohydrates tested do not prove to be inhibitors. The value for the energy of activation is 38 kJ/mol (9 kcal/mol); the Q10 is 1.5. The results of heat inactivation of altronate oxidoreductase (58.5 °C) indicate homogeneous enzyme activity in crude extract. Thermal inactivations also indicate that the same enzyme, altronate oxidoreductase, is induced by galacturonate and glucuronate, and catalyzes the direct reactions with NADH or NADPH. Finally, it has been confirmed by heat inactivation that there is no interference between specific assays of altronate and mannonate oxidoreduetases. Compounds such as NADH, NADPH, altronate and mannonate protect enzymatic activity from degradation by heat, whereas NAD+, tagaturonate and fructuronate do not. NADH, in particular, is effective as a stabilizer; this ability is proportional to its concentration. Enzyme inhibition with para-chloromercuribenzoate is non-competitive and the apparent Ki is 1 mM. para-Chloromercuribenzoate also inactivates altronate oxidoreductase indicating homogeneous activity and specificity of the assay method in crude extracts. Chromatographic properties of the enzyme are identical whether the inducer is galacturonate or glucuronate. Using paper chromatography, the reaction product of enzyme action on D-tagaturonate is identified as D-altronate. [ABSTRACT FROM AUTHOR]

The paper describes the mode of infection and subsequent deterioration of spruce root wood by Forties annosus using light and electronmicroscopic observations. In the secondary xylem the overall penetration of cell walls is effected by means of microhyphae which produce boreholes. The degradation of cell walls is initiated in the S2 layer by diffusion of enzymes along the cellulose fibrils with subsequent hydrolysis of the amorphic incrusting substances.