PMID: 2114824Aug 1, 1990Paper

Pyruvate:NADP+ oxidoreductase from Euglena gracilis: mechanism of O2-inactivation of the enzyme and its stability in the aerobe

Archives of Biochemistry and Biophysics
H InuiS Kitaoka

Abstract

O2-inactivation of pyruvate:NADP+ oxidoreductase from mitochondria of Euglena gracilis was studied in vitro, and a mechanism which consists of two sequential stages was proposed. Initially, the enzyme is inactivated by the direct action of O2 in a process obeying second-order kinetics. Although the catalytic activity for pyruvate oxidation is lost by this initial inactivation, NADPH oxidation with artificial electron acceptors still occurs. Subsequently, a secondary, O2-independent inactivation occurs, rendering the enzyme completely inactive. Pyruvate stimulates the O2-inactivation while CoA and NADP+ protect the enzyme from O2. The O2-inactivation is accelerated by reduction of the enzyme with pyruvate and CoA. Reactivation of the O2-inactivated enzyme was studied in Ar by incubation with Fe2+ in the presence of some other reducing reagent such as dithiothreitol. The evidence obtained indicates that the partially inactivated enzyme, which retains catalytic activity for NADPH oxidation, can be reactivated, but the completely inactivated enzyme is not. When Euglena cells were exposed to 100% O2 the enzyme in the cells was inactivated by O2, but the rate was quite slow compared with that observed in vitro. The enzyme inactivated...Continue Reading

Citations

Nov 6, 2002·Trends in Biochemical Sciences·Aloysius G M TielensWilliam Martin
Dec 5, 2003·European Journal of Biochemistry·Ricardo Jasso-Chávez, Rafael Moreno-Sánchez
Jan 31, 2006·The Journal of Eukaryotic Microbiology·Jose S Rodríguez-ZavalaRafael Moreno-Sanchez
Feb 24, 2015·Journal of Hazardous Materials·M Geovanni Santiago-MartínezRicardo Jasso-Chávez
Jul 1, 1991·Archives of Biochemistry and Biophysics·S Shigeoka, Y Nakano
Dec 10, 2013·Biochimie·Takashi Makiuchi, Tomoyoshi Nozaki
Mar 12, 2004·The Journal of Biological Chemistry·Meike HoffmeisterWilliam Martin
Mar 8, 2003·Archives of Biochemistry and Biophysics·Masami NakazawaKazutaka Miyatake
Apr 1, 1991·Archives of Biochemistry and Biophysics·H InuiS Kitaoka

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