Chaetopterus Photoprotein: Crystallization and Cofactor Requirements for Bioluminescence

Abstract
The Chaetopterus photoprotein has been isolated in an amorphous form (molecular weight, 120,000) whlich in (NH4)2SO4 sollutionl converts to a crystalline form (molecular weight, 184,000) having the same specific light-emittinig activity; quantum yields are 0.0093 and 0.0143, respectively. Two new cofactor reqluirements have been separated fronm impure extracts: a macromnolecule resembling a nucleoprotein, and a lipid-like substance.