PROTEIN FACTOR INHIBITING ACTIVATION OF PROPHENOLOXIDASE WITH NATURAL ACTIVATOR AND ITS PURIFICATION

Fractionation of the crude prophenol oxidase solution from prepupae of housefly, Musca domestica vicina Maquart, was performed. The soluble fraction of 40% saturation of ammonium sulfate contained a certain factor able to inhibit the activation of prophenol oxidase A with natural activator from aged pupae. The factor apparently was a protein and was tentatively named Factor N. Purification of Factor N by gel filtrations 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 seimentation constant of 5.4 S.