Stability of Luminous Substances of Luminous Animals.

Abstract

It is about ten years (1918) since I first collected the luminous ostracod crustacean, Cypridina, extracted the luminous materials, luciferin and luciferase, and set some of the extracts aside for later testing as to stability. The animals are collected and dried quickly over CaCl₂. When powdered and moistened a bright bluish luminescence appears which is as intense with the 1918 material tested in 1928 as it was in 1918. This powder contains both luciferin and luciferase and light results from mixing the 2 substances in water containing oxygen. Luciferin solution is obtained by making a hot water extract of Cypridina. Heating destroys the luciferase, which can be extracted from Cypridina with cold water. The luciferin, which dissolves at the same time, is allowed'to oxidize in the air, leaving luciferase alone in solution.

Sterile luciferin extracts made in 1918 and kept under a 3 inch layer of vaselin, to prevent oxidation, gave a good luminescence when luciferase was added to them in 1928. So long as oxidation is prevented, luciferin in water solution appears perfectly stable. A flask of luciferin solution was evacuated and the glass sealed. This flask was then heated in a water bath at 100° C. for one hour and set aside, sealed, January 22, 1924. On October 16, 1928 the flask was opened to the air. No luminescence appeared on opening, but when luciferase was added, a brilliant light appeared. Evidently boiling does not destroy luciferin if air is absent. Absolute alcohol extracts of luciferin kept in air show no luminescence after a few weeks when mixed in small quantity with luciferase solution. A slow oxidation of luciferin must take place.