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The properties and enzymic activity of endoglucanases (EC 3.2.1.4) of the fungus Trichoderma reesei were studied by means of immunological methods and by using polyglycosidic substrates. Endoglucanases exist in the culture liquid as a series of immunologically related components. The most active endoglucanase component has an Mr of 43 000 and pI value of 4.0. The most abundant components have a value of pI about 5.0, an Mr of 56 000-67 000 and specific activity only one-fifth of that of the pI-4.0 component. During purification and storage the endoglucanases are spontaneously modified; the relative proportion of components having greater Mr values, more alkaline pI values and lower specific activities is increased. The hexose content of the endoglucanase components is 2-7%. Endoglucanases hydrolyse soluble β-1,4 glycans. The enzymes described here differ from endoglucanase preparations described previously in not showing activity towards insoluble substrates. The role of endoglucanases in wood hydrolysis is consequently limited to the stage where wood constituents are already in soluble form.

A 1,4-beta-D-glucan cellobiohydrolase (EC 3.2.1.91) was purified from the culture liquid of Trichoderma reesei by using biospecific sorption on amorphous cellulose and immunoaffinity chromatography. A single protein band in polyacrylamide-gel electrophoresis and one arc in immunoelectrophoresis corresponded to the enzyme activity. The Mr was 65 000. The pI was 4.2-3.6. The purified enzyme contained about 10% hexose. The enzyme differs from previously described cellobiohydrolases in being more effective in the hydrolysis of cellulose.

One oxidase (EC 1.10.3.2) and three lignin peroxidases (EC 1.11.1.-) were purified from the culture liquid of the white-rot fungus Phlebia radiata Fr. All the enzymes were glycoproteins. The oxidase had Mr 64,000 and the lignin peroxidases I, II and III had Mr values 42,000, 45,000 and 44,000 respectively. The lignin peroxidases were found to share common antigenic determinants: lignin peroxidases II and III were serologically indistinguishable and lignin peroxidase I was related but distinguishable. The oxidase did not share any immunological properties with the lignin peroxidases. Lignin peroxidases of Phlebia contain protoporphyrin IX as a prosthetic group. In the presence of H2O2 and an electron donor, veratryl alcohol, lignin peroxidases exhibit spectral shifts analogous to those of animal catalase (EC 1.11.1.6). Phlebia enzymes show optimal activity at pH 3-4.5 at 40 degrees C and are stable in the pH range 5-6. They modify Kraft lignin and phenolic compounds containing hydroxy and methoxy groups.

Insoluble xylan was prepared from ground birch (Betula pubescens) pulp by alkali extraction and precipitation with ethanol. The only sugar detected after acid hydrolysis of the preparation was xylose. The insoluble xylan was used as substrate in a nephelometric assay to determine the xylanase (EC 3.2.1.8, 1,4-beta-D-xylan xylanohydrolase and EC 3.2.1.37, 1,4-beta-D-xylan xylohydrolase) activities of Aspergillus and Trichoderma enzymes. The nephelometric method is reliable in evaluating xylanase hydrolysis of insoluble xylan.