LIGHT-EMITTING MOLECULE IN A NEW PHOTOPROTEIN TYPE OF LUMINESCENCE SYSTEM FROM THE EUPHAUSID SHRIMP Meganyctiphanes norvegica

Abstract

The data in this paper indicate that the light-emitter of the Meganyctiphanes system is either the fluorescent substance itself or some slightly and reversibly altered state of this substance. Thus the emission spectrum of fluorescence, excited at the excitation peak of 392[plus or minus] 2 m[mu], has a slightly broader distribution than the emission spectrum of the luminenscence reaction but otherwise the 2 emission spectra are closely the same, with identical maxima at 476 m[mu]. The UV absorption spectrum was found to be in good agreement with the excitation spectrum. It is interesting to note that independent measurements, by means of a series of interference filters and a photomultiplier, of the spectral distribution of terminal glows in photogenic organs of dead specimens and in homogenates show a bimodal emission curve, with a sharp primary peak near 476 m[mu] and a second, lower peak between 520 and 540 m[mu]. The 2 peaks are at corresponding wavelengths in 3 species of euphausids: M. norvegica, Euphausia pacifica, and Thysonoessa raschii. The primary peak agrees with that of the highly purified fluorescent substance of Meganyctiphanes which lack the second. The nature of the Meganyctiphanes system, wherein a relatively small organic molecule catalyzes the oxidative decomposition of a large protein molecule with the liberation of a large amount of energy, has some implications which perhaps merit further inquiry and consideration in regard to biological reactions in general.