PURIFICATION AND CHARACTERIZATION OF CHOLINESTERASE FROM EISENIA FOETIDA

Cholinesterase from the Triton X-100 extract of Eisenia foetida was purified to electrophoretic homogeneity by extraction with PEG 2 000/potassium phosphate buffer, ion-exchange chromatography and gel filtration. The purified enzyme was found to be a kind of glycoproteins. The Mr determined by gel filtration was 59 000 and by SDS-PAGE was 58 000. The contents of acidic amino acid and basic amino acid were about 24% and 12%, respctively. Ultraviolet spectrum showed a maximum absorption at 272 um. The enzyme with optimum temperature of 39℃ was unstable when heated. It exhibited optimum activity at pH 7. 8 and kept stable between pH 7. 8 ~ 8. 0. The Michaelis constant for acetylthiocholine iodide was 88 μmol/L. The enzyme activity affected slightly by Mg2+,Ca2+ and Mn2+ was inhibited by excess substrate and strongly by DFP.