Ⅴ.orientalis 518 strain was cultured in liquid medium

with shaking at 20℃ for 16 hours. Cells were harvested at the late log phase by cen-trifugation and lysed by addition of cold distilled water to the cell paste. Then

it Was treated with ultrasonic in an ice bath.The rough luciferase was isolated from the above suspension of cells. Then it was purified by DEAE-Cellulose chromatography as well as DEAE-sephadex chromatograhy. By means of sephadex G-100 gel filtration

it has been determined that the molecular weight of this luciferase is 87000 and by means of SDS-PAGE it has been determined that there are two subunits αand β in luciferase and their molecular weight are 44000 and 41000 respectively.The reaction system contains the compounds with the following concentration: 5.1μuM FMN

3.4mM sodium dithionite

2.2μM catalase

1.9 mM decanal and 85mM H

2

O

2

. Some properties of the luciferase were studied. The maximun luciferase activity was obtained at 18℃

pH 6.8. The luciferase was sensitive to heat treatment. It lost its catalititc activity at above 25℃. The results showed that the luciferase lost above 95% of its activities after pre-treatment at 40℃ for 40 minutes.The luciferase had a luminescent peak at 490nm. It was consistent with previous reports.