抄録
Fractionation of the crude prophenoloxidase solution from prepupae of housefly, Musca domestica vicina Maquart, was carried out. The soluble fraction of 40% saturation of am-monium sulfate contained a certain factor being able to inhibit the activation of prophe-noloxidase A with natural activator from aged pupae. The factor seemed to be a protein and was named Factor N tentatively.
Purification of Factor N by gel filtration on Sephadex G-75 and sucrose density gradient ultracentrifugation resulted in an 18.2% of the yield of the activity and a 21.8-fold increase in the specific activity. The purified preparation of Fractor N had a sedimentation constant of 5.4 S.
