A method to detect or determine the presence or activity of a nonluciferase enzyme in a sample comprising: a) providing a first mixture comprising a sample, a first reaction mixture for a nonluciferase enzyme-mediated reaction, and a derivative of 2-cyano-6-substituted benzothiazole which includes a substrate for the nonluciferase enzyme, wherein the first mixture does not include a cofactor specific for the activity of the nonluciferase enzyme, and wherein the derivative, when in the presence of D-cysteine and a non-luciferase enzyme, yields a product that is a bioluminogenic substrate for a beetle luciferase in the absence of the cofactor; b) contacting at least a portion of the first mixture with a second reaction mixture for a beetle luciferase-mediated reaction which includes D-cysteine, so as to yield a second mixture; and c) comparing luminescence in the second mixture to luminescence in a control mixture in which a third mixture having the sample, a first reaction mixture for the nonluciferase enzyme-mediated reaction, the derivative of 2-cyano-6-substituted benzothiazole, and a cofactor specific for the nonluciferase enzyme, is contacted with a reaction mixture for the beetle luciferase-mediated reaction which includes D-cysteine, thereby detecting or determining the presence or amount of the nonluciferase enzyme in the sample; and wherein the derivative of 2-cyano-6-substituted benzothiazole is a compound of formula I wherein R 1 is OH, OR x, OSO 2 R x, or NHR x; R 2 is (C 1 -C 3)alkyl, trifluoromethyl, amino, nitro, or halo; n is 0, 1, 2, or 3; and R x is aryl or (C 1 -C 3)alkylaryl wherein the aryl is optionally substituted with one to five halo, hydroxy, nitro, or amino groups. a) providing a first mixture comprising a sample, a first reaction mixture for a nonluciferase enzyme-mediated reaction, and a derivative of 2-cyano-6-substituted benzothiazole which includes a substrate for the nonluciferase enzyme, wherein the first mixture does not include a cofactor specific for the activity of the nonluciferase enzyme, and wherein the derivative, when in the presence of D-cysteine and a non-luciferase enzyme, yields a product that is a bioluminogenic substrate for a beetle luciferase in the absence of the cofactor; b) contacting at least a portion of the first mixture with a second reaction mixture for a beetle luciferase-mediated reaction which includes D-cysteine, so as to yield a second mixture; and c) comparing luminescence in the second mixture to luminescence in a control mixture in which a third mixture having the sample, a first reaction mixture for the nonluciferase enzyme-mediated reaction, the derivative of 2-cyano-6-substituted benzothiazole, and a cofactor specific for the nonluciferase enzyme, is contacted with a reaction mixture for the beetle luciferase-mediated reaction which includes D-cysteine, thereby detecting or determining the presence or amount of the nonluciferase enzyme in the sample; R 1 is OH, OR x, OSO 2 R x, or NHR x; R 2 is (C 1 -C 3)alkyl, trifluoromethyl, amino, nitro, or halo; n is 0, 1, 2, or 3; and R x is aryl or (C 1 -C 3)alkylaryl wherein the aryl is optionally substituted with one to five halo, hydroxy, nitro, or amino groups.