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Atternaria sp. was isolated from soil and crude cellulases were prepared from wheat bran culture of the fungus. The activities of the crude enzyme were studied on five different substrates and some physical properties were also examined, crude enzymes were purified by column chromatography on DEAE Sephadex and Sephadex, Isozymes were separated some of which were active specifically on DEAE cellulose and some were primarily active on cellulose and CM-cellulose. The optimal points of pH and temperature for the crude enzyme were varied depending on the substrates ; On cellulose they were at pH 6.0 and 40℃, on CM-cellulose at pH´s 4.0 and 6.0 and 60℃, and on DEAW-cellulose at pH 5.0 and 50℃. Two active fractions, F-1 and F-II on Na-CMC was used as substrate the Km values of crude enzyme, F-I and F-II were calculated to be 4 × 10^-5, 1.1 × 10^-4, and 1.25 × 10^-4mM respectively. The Ki value of Cu^++ for crude enzyme was 4 × 10^-4mM, while that of Nm^++ while in the same concentration of Mn^++ it reached to 91%. Some 57% activity of F-1 was inhibited in 2 mM Cu^++, whereas it was inhibited as much as 81% in the same concentration above the concentration of 0.3 mM with its activity reaching up to 137% in 2 mM. On the other hand the F-11 was inhibited by the presence of Mn^++ and some 67% activity was inhibited at 2mM.
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