Correlation between hemin content and the chemiluminescent luminol reaction with bacteria.

Protohemin and covalently bound hemin were determined in eight aerobic bacterial strains. A good correlation between protohemin content and luminol reactivity was found. The ratio of luminol reaction to protohemin for the eight investigated strains was essentially identical to that of pure protohemin, 0.7 X 10(16) mV/mol. Covalently bound hemin contributed to the chemiluminescence to a minor extent only (0.7 X 10(14) mV/mol, in accordance with earlier observations of the lower reactivity of cytochrome c and related compounds. A difference in reaction kinetics of the luminol reaction with covalently bound hemin (slower reaction than protohemin) and protohemin was observed in vivo as well as in vitro. The phenomenon could be used to differentiate between strains with different hemin composition.