A kinetic method will be utilized probe crude microsomal enzymatic mixtures in order to obtain information on the nature and number of enzymes present in the mixture. Quantitative changes produced in the system such as the use of inducing agents and inhibitors will be used to explore the specific catalytic properties of individual enzymes. Such information will increase our understanding of the catalytic nature of these enzymes and suggest ways in which chemically induced toxicities caused by the generation of reactive intermediates in the process of biotransformation can be circumvented.