The proposed program of research is the second year of a project designed to identify the mutagenic substances formed in the boiling of beef stock and the cooking of beef tissues, and to establish the mechanisms of their formation. The investigations use the Ames Salmonella assay to follow the mutagens through isolation and purification processes, and to monitor experiments on the mechanisms of formation of the beef extract mutagens. In the first year a process for isolating two pure mutagens from crude beef extract was developed, and preliminary experiments with 14C labbelled amino acids designed to identify the parent compounds of the mutagens were begun. The second year's work will consist of physical analyses to determine the molecular structure of the two major mutagens; using Fourier-transform NMR, infrared spectrometry and high resolution mass spectrometry. The identified structures will be confirmed by comparisons with compounds synthesised in the laboratory. The experiments and labelled compounds will also be continued in the second year, with the goal of identifying the parent compounds for the mutagens and determining their routes of formation.