FOUR FIGURE6
INTRODIlCTION
Since it has been shown that sulfanilamide readily inhibits bacterial luniinesccncc, in a manner resembling that of narcotics in general (Jolinson and Moore, '41), its action on the purified luciferin-luciferase system of Cypridina assumes especial interest. A similar effect of the drug on this extracted system, which cannot as yet be obtained from the luminous bacteria, was predicted, and has been confirmed in the present investigation. With Cypridina extracts it has been possible to study, under greatly simplified conditions, the influence of substrate (luciferin) concentration, as well as concentration of the drug, on the inhibition. I n addition to sulfanilamide, sulfapyridine and sulfathiazol were studied, both bccause of their therapeutic importance and the possible significance of molecular configuration to the luminescence inhibition. Finally, bccause of their interest in relation to the fundamental mechanism of sulfonamide action, p-aminobeiizoic acid (PAB) and urethane were also included. The former compound has been shown to exert growth-promoting and anti-sulfanilamide effects in cultures, and has been considered the site of sulfanilamide inhibitions through competitive action of the structurally related molecules for some common enzyme in the organisms (Woods and Fildes, '40; Woods, '4U; Fildes, '40). The latter compound, however, has been found to exert many parallel effects, and a n interpretation of the action of both in relation to general phenomena of narcosis has been suggested (Johnson, '42).
With unpurified extracts of dried Cypridina, Taylor ( '34) has shown that urethane lowers the velocity constant of the luminescent oxidation, and in high concentration may decrease the total light emitted. Low concentrations, however, "markedly increased" the velocity coilstant 'Aided in part h?a grant t o one of us (F. β¬1. J . ) from the Penrnse Fund of thc Aiiicrirrjn Philosophicnl Society.