Dependency on serine concentration of the activity of tryptophan synthase. Cooperative properties.

The activity of the enzyme tryptophan synthase from Escherichia coli was tested as a function of the concentration of L-serine which serves as a substrate in the indole to tryptophan reaction as well as for the L-serine deaminase activity. L-Serine binding was found to follow the pattern of negative cooperativity both by kinetic and by equilibrium methods. The enzyme kinetic data support the view that a rapid equilibration model for the enzyme . substrates complex formation is not strictly obeyed.