A typical natural phenomenon, probably a unique mating signal by the “firefly,” also exists in other living species, namely, bacteria, protozoa, fungi, and worms, in the forms that emit visible light. In most cases, the
nature of the luminescent light varies in color and intensity; but chem­ical pathways are, to a great extent, common. The chemical products responsible for giving out different colors are different and are not yet fully known.

A heat-labile simple protein enzyme luciferase (MW 105) makes a complex (luciferyl adenylate E) with reduced luciferin, in the presence of ATP (Mg2+), which subsequently breaks down into different products in the presence of molecular oxygen. This results in the excitation of luciferin to a high-energy state. On return of the same to the ground state, emission of visible light produces bioluminescence (see Fig. 1.13).

LH2 + ATP (Mg2+) + E ^ LH2 — AMP — E + PPi
LH2 — AMP — E + O2 ^ Products + Light

The phenomenon appears to be insignificant but a substantial supply of luciferin, ATP (Mg2+), and a little enzyme can deliver an appreciable luminescence of practical use. Whether luciferin, luciferase, and ATP may also be harvested from animal resources, or the chemical compo­nents may be synthesized economically and the enzyme can be pro­cured from flies, remains a matter of investigation and development. Like bee-keeping, culture of “fireflies” is very likely to become a prof­itable art. The dream of producing high voltage by animal tissues, imi­tating the electric eel, may come true in the near future; the fundamentals are known, but economic viability is not assured, hence not discussed here.

OH

I

C—O — P—O—Ribose-Adenine

II II

OO

LH2-Adenylate

Figure 1.13 Firefly bioluminescence.