Abstract: Novel pro-drugs and methods for their use to alter the growth and biological characteristics of living cells, tissues, or whole organisms are described. The methods allow for selective activation of the pro-drugs at or near transformant host cells expressing a gene for an enzyme that activates the pro-drugs. Pro-drugs according to a preferred embodiment of the invention are conjugates of a bioactive compound and a chemical group that is capable of being cleaved from the bioactive compound by action of an enzyme. Methods according to this invention include, (a) introducing into targeted cells a gene encoding an enzyme and (b) administering a pro-drug, wherein the enzyme releases the pro-drug from conjugation. In a preferred embodiment of the invention, the gene encoding the enzyme is a marker gene.

Abstract: The subject invention provides substrates useful for analyzing the metabolic activity in cells by improving the retention of a detectable reporter molecule only in intact cells where a particular enzyme is present. In particular, improved retention results from a two part process involving conjugation of haloalkyl-substituted derivatives of a reporter molecule with intracellular cysteine-containing peptides while unblocking the reporter molecule. The substrates have the formXR-SPACER-REPORTER-BLOCKwherein -BLOCK is a group selected to be removable by action of a specific analyte, to give REPORTER spectral properties different from those of the substrate,-REPORTER- is a molecule that, when no longer bound to BLOCK by a BLOCK-REPORTER bond, has spectral properties different from those of the substrate,-SPACER- is a covalent linkage, andXR- is a haloalkyl moiety that can covalently react with an intracellular thiol (Z-S-H) to form a thioether conjugate (Z-S-R-).

Abstract: The subject invention provides substrates useful for analyzing the metabolic activity in cells by improving the retention of a detectable reporter molecule only in intact cells where a particular enzyme is present. In particular, improved retention results from a two part process involving conjugation of haloalkyl-substituted derivatives of a reporter molecule with intracellular cysteine-containing peptides while unblocking the reporter molecule. The substrates have the form XR-SPACER-REPORTER-BLOCK wherein -BLOCK is a group selected to be removable by action of a specific analyte, to give REPORTER spectral properties different from those of the substrate, -REPORTER- is a molecule that, when no longer bound to BLOCK by a BLOCK-REPORTER bond, has spectral properties different from those of the substrate, -SPACER- is a covalent linkage, and XR- is a haloalkyl moiety that can covalently react with an intracellular thiol (Z-S-H) to form a thioether conjugate (Z-S-R).