Properties of Bursicon: An Insect Protein Hormone That Controls Cuticular Tanning

On gel filtration the retention volume of bursicon indicates a molecular weight of about 40,000. On disc electrophoresis bursicon migrates toward the anode and appears at an R F (relative to the marker dye) of 0.3 to 0.4. The properties of fractions with bursicon activity in blood, brain, and ganglion of a fly ( Sarcophaga bullata ), and in blood, ganglion, and corpora cardiaca of a roach ( Periplaneta americana ) are similar, but not identical. Bursicon in the blood is more heat labile, and the activity in brain and corpora cardiaca shows two peaks in electrophoresis, instead of one as in the other fractions.