Irepex lacteusのcellulase系について

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A partially purified cellulase preparation was obtained from a culture filtrate of Irpex lacteus (Polyporus tulipiferae) by alternately repeating the precipitation with ammonium sulfate and acetone.It showed a high activity toward carboxymethyl cellulose(CMC), but still slightly contaminated with β-glucosidase.The preparation wes subjected to fractionation by different procedures to obtain further information about the properties of isozymic entities of Irpex cellulase Starch-zone electrophoresis of this sample gave several components. One of them showed relatively high saccharifying activities toward CMC, Walseth cellulose and Whatman cellulose powder.The component also participated in the activity for decrease in the weight of cellulose powder. Two of these components, however, were found to be very active on cellulose powder but little on CMC and Walseth cellulose. Furthermore, one of two main components occuring in the electrophoretic patterns of a crude cellulase preparation was non found in the purified sample.DEAE-celluloes column chromatography separated the partially purified sample into three main components, each of which showed saccharifying activties toward CMC and Avicel, though different in their rates. In contrast, a liquefying activity was found only in the second component to a remarkable extent and pratically absent in the first component. The former component, therefore, appears to be a "more random" type and the latter a "less random" one. It is of interest that the saccharification of Avicel by the component of the latter type was much greater than by the former. Possibly Avicel may be more accessible to the "less random" cellulase than to the other, since each particle of Avecel is crystalline but exposes a large number of terminal parts of the molecular chains. The three components did not show the activity for decrease in the weight of cellulose powder even after they were concentrated to a small volume, and components responsible for this activity seemed to be adsorbed to the column, since the starting material possessed it.Hydroxyapatite column chromatography imperfectly resolved the purified sample into several componets which seemed to be of "more" or "less" random type.The component eluted at first showed mainly a saccharifying activity toward CMC, but several fractions which followed it had a predominantly liquefying activity. In contrast, the other components appeared to have activities toward Walseth cellulose and cellulose powder besides both kinds of CMC-ase activity.Several fractions eluted nearly in the middle of elution appeared to contain a few components of a high activity toward CMC and Walseth cellulose, and they were particulary high in the activity for decrease in the weight of cellulose powder. The activiety seemed, on the basis of their patterns, to be effected by the combined work of CMC-ases of different degree of randomness. The "more random" components may at first easily attack the amorphous regions of cellulose materials , and the "less random" ones may then react with the terminal parts which were newly produced by the action of the former. Thus, it appears that Irpex cellulase is composed of several isozymes of a wide or a narrow substrate specificity, and that they effectively perform the breakdown of substrates by a cooperative work in which "more" and "less" random hydrolyses are involved.
社団法人日本生物工学会の論文
1964-06-15

Irepex lacteusのcellulase系について

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