INACTIVATION OF BACTERIAL LUCIFERASES BY N-ETHYLMALEIMIDE

The kinetics of inactivation of luciferases from four species of luminescent bacteria by the thiol reagent N-ethylmaleimide were investigated The dependencies of inactivation on ionic strength differed among the enzymes. Increasing the molarity of the buffer increased the rate of inactivation of all luciferases except that of Vibrio harveyi. Modification of Photobacterium phosphoreum luciferase decreased the maximal intensity of bioluminescence, whereas modification of Photobacterium leiognathi and Vibrio fischeri luciferases in high ionic strength buffers decreased the maximal intensity of bioluminescence and changed the luminescence decay rate constant. High ionic strength apparently alters the conformational states of the luciferases.