Although luminescence of Cypridina lucif erin by oxidants mhcn dissolved in ethyl alcohol has been observed, no conditions have been previously found under which Cypridina luciferin will emit light in aqueous solutions in the absence of Cypridina luciferase. All attempts to observe luminescence during rapid spontaneous oxidation in water at high temperature or in presence of oxidizing agents from all positions on the redox scale have becn in vain (Harvey, '28). I n view of the progress in purification of Cypridina luciferin which has been effected in recent years, the action of the various oxidants studied in 1928 has been reinvestigated with luciferin prepared by Anderson's ( ' 3 5 ) two cycle benzoylation procedure. The following oxidants were tested as solids or in dilute aqueous solution added to the aqueous luciferin, both without and with 2% H,O,: KMnO,, K,Cr,07, K,Fe(CN),, Ca hypochlorite, K persulphate, XnO,, BaO,, 1% osmic acid, platinized asbestos, cytochrome C (Sigma) and hemin (Nutritional Biochemicals). These oxidants were chosen because they are effective, either alone or with H,O,, in causing chemiluminescence of various organic compounds, but in no case did light appear with Cypridina luciferin solutions, although the eye is not as sensitive as modern scintillation counters in detecting low intensity emission.
This research has been in part supported by a contract between the Office of For properties of Cypridina heiferin, see Chase ( '48).