Luciferase of the Scyphozoan Medusa Periphylla periphylla

Two types of luciferase that catalyze the luminescent oxidation of coelenterazine were isolated from the marginal exumbrella epithelium (lappet) and the ovary of Periphylla periphylla; they were designated luciferase-L and luciferase-O, respectively. Luciferase-L (Mr 32,000), probably derived from highly specialized photocytes, was very resistant to heat, and its activity was little affected by boiling; but it was unstable in solutions of low ionic strength if bovine serum albumin was not included in the solvent. Luciferase-O (Mr 75,000) occurred in the eggs in association with particulate matter, and was solubilized and extracted with a buffer containing 2 M guanidine hydrochloride; the enzyme was highly stable in this strongly denaturing solvent. The intensities of the coelenterazine luminescence catalyzed by both luciferases were maximal at pH 7.8 and in the presence of about 1 M NaCl. The quantum yield of coelenterazine was estimated to be 0.14 with luciferase-L (emission max. at 465 nm) and 0.12 with luciferase-O (emission max. at 470 nm). The luminescence caused by both luciferases was strongly inhibited by Cu2+ and thiol compounds.