Abstract: The present invention provides a method for reducing undesirable light emission from a sample using at least one photon producing agent and at least one photon reducing agent (e.g. dye-based photon reducing agents). The present invention further provides a method for reducing undesirable light emission from a sample (e.g., a biochemical or cellular sample) with at least one photon producing agent and at least one collisional quencher. The present invention also provides a method for reducing undesirable light emission from a sample (e.g., a biochemical or cellular sample) with at least one photon producing agent and at least one quencher, such as an electronic quencher. The present invention further provides a method of determining bound and free analyte in a sample using at least one photon reducing agent. The present invention also provides a method of screening test chemicals in fluorescent assays using photon reducing agents.

Abstract: The invention provides a compound, useful as an optical probe or sensor of the activity of at least one cytochrome P450 enzyme, and methods of using the compound to screen candidate drugs, and candidate drugs identified by these methods. The optical probe of the invention is a compound having the generic structure Y-L-Q, wherein Y is selected from the group consisting of Q as herein defined, saturated C.sub.1 -C.sub.20 alkyl, unsaturated C.sub.1 -C.sub.20 alkenyl, unsaturated C.sub.1 -C.sub.20 alkynyl, substituted saturated C.sub.1 -C.sub.20 alkyl, substituted unsaturated C.sub.1 -C.sub.20 alkenyl, substituted unsaturated C.sub.1 -C.sub.20 alkynyl, C.sub.1 -C.sub.20 cycloalkyl, C.sub.1 -C.sub.20 cycloalkenyl, substituted saturated C.sub.1 -C.sub.20 cycloalkyl, substituted unsaturated C.sub.1 -C.sub.20 cycloalkenyl, aryl, substituted aryl, heteroaryl and substituted heteroaryl; L is selected from the group of (--O(substituted ortho-phenyl)CR.sup.2 H).sub.p --, (--O(substituted meta-phenyl)CR.sup.2 H).sub.

Abstract: Substrates for .beta.-lactamase of the general formula I ##STR1## in which one of X and Y is a fluorescent donor moiety and the other is a quencher (which may or may not re-emit); R' is selected from the group consisting of H, lower (i.e., alkyl of 1 to about 5 carbon atoms) and (CH.sub.2).sub.n OH, in which n is 0 or an integer from 1 to 5; R" is selected from the group consisting of H, physiologically acceptable metal and ammonium cations, --CHR.sup.2 OCO(CH.sub.2).sub.n CH.sub.3, --CHR.sup.2 OCOC(CH.sub.3).sub.3, acylthiomethyl, acyloxy-alpha-benzyl, delta-butyrolactonyl, methoxycarbonyloxymethyl, phenyl, methylsulphinylmethyl, beta-morpholinoethyl, dialkylaminoethyl, acyloxyalkyl, dialkylaminocarbonyloxymethyl and aliphatic, in which R.sup.2 is selected from the group consisting of H and lower alkyl; A is selected from the group consisting of S, O, SO, SO.sub.2 and CH.sub.2 ; and Z' and Z" are linkers for the fluorescent donor and quencher moieties. Methods of assaying .beta.

Abstract: Fluorogenic substrates of the general formula I ##STR1## in which one of X and Y is a fluorescent donor moiety and the other is a quencher (which may or may not re-emit); R' is selected from the group consisting of H, lower (i.e., alkyl of 1 to about 5 carbon atoms) and (CH.sub.2 OH).sub.n OH, in which n is 0 or an integer from 1 to 5; R" is selected from the group consisting of H, physiologically acceptable metal and ammonium cations, --CHR.sup.2 OCO(CH.sub.2).sub.n CH.sub.3, --CHR.sup.2 OCOC(CH.sub.3).sub.3, acylthiomethyl, acyloxy-alpha-benzyl, delta-butyrolactonyl, methoxycarbonyloxymethyl, phenyl, methylsulphinylmethyl, beta-morpholinoethyl, dialkylaminoethyl, acyloxyalkyl, dialkylaminocarbonyloxymethyl and aliphatic, in which R.sup.2 is selected from the group consisting of H and lower alkyl; A is selected from the group consisting of S, O, SO, SO.sub.2 and CH.sub.2 ; and Z' and Z" are linkers for the fluorescent donor and quencher moieties. The substrates are useful in conjunction with .beta.