Analysis of Strain #4 Arg- mutants

    Arg- Strain #4 can grow with the addition of any of the three amino acids. Therefore, it must affect the production of enzyme A, the first step in the pathway. Absence of a functional enzyme A prevents synthesis from some precursor substance of X, which therefore prevents subsequent synthesis of Y or Z. Addition of any of X, or Y, or Z will permit growth, since enzymes B & C are functional, and can convert these substances to arginine. However, analysis of this strain provides no information about the relative order of arg, cit, and orn in the pathway.

All text & figure material © 2008 by Steven M. Carr