Oxidative inactivation of yeast fructose-1,6-bisphosphatase

Active, non-phosphorylated fructose-1,6-bisphosphatase from yeast is partially inactivated by two different mixed-function oxidation systems: the ascorbate-FeC13-02 system described by Levine (Levine, R. (1983) J. Biol. Chem. 258, 11823-11827) and the NADH oxidase-NADH-FeC13-O2 system described by Fucci et al. (Fucci, L., Oliver, C.N., Coon, M.J., and Stadtman, E.R. (1983) Proc. Natl. Acad. Sci. 80, 1521-1525). Fructose-2,6-bisphosphate (1 microM) or histidine (10 mM) partially protect from oxidative inactivation. The inactivation is characterized by the following changes in the kinetic properties of fructose-1,6-bisphosphatase: decrease of the ratio of activity at pH 7 to that at pH 9 and decrease of the ratio of activity with 10 mM Mg2+ to that with 2 mM Mn2+. These changes of the kinetic properties are very similar to the ones previously observed following phosphorylation (Holzer, H. (1984) in "Enzyme regulation by reversible phosphorylation - further advances" (P. Cohen, ed.) pp. 143-154, Elsevier Science publisher) and limited proteolysis of fructose-1,6-bisphosphatase with yeast proteinase B (Pohlig, G., Schäfer, W., v. Herrath, M. and Holzer, H. (1984) in "Current topics in cellular regulation" (S. Shaltiel and P. Boon Chock, eds.) in press).