The Thermodynamics of Xanthine Oxidoreductase Catalysis

The thermodynamics of xanthine oxidoreductase catalysis.

Xanthine oxidoreductase is a complex enzyme found in a wide range of organisms. Recent interest in this enzyme stems from its ability to produce reactive oxygen species under a range of conditions. It is found as a homodimer, each unit containing a molybdopterin cofactor, two iron sulfur centers, and FAD. The enzyme can exist in two forms that differ primarily in their oxidizing substrate speci...

The crystal structure of xanthine oxidoreductase during catalysis: implications for reaction mechanism and enzyme inhibition.

Molybdenum is widely distributed in biology and is usually found as a mononuclear metal center in the active sites of many enzymes catalyzing oxygen atom transfer. The molybdenum hydroxylases are distinct from other biological systems catalyzing hydroxylation reactions in that the oxygen atom incorporated into the product is derived from water rather than molecular oxygen. Here, we present the ...

Regulation of the Human Xanthine Oxidoreductase Gene

Regulation of xanthine oxidoreductase by intracellular iron.

Xanthine oxidoreductase (XOR) may produce reactive oxygen species and play a role in ischemia-reperfusion injury. Because tissue iron levels increase after ischemia, and because XOR contains functionally critical iron-sulfur clusters, we studied the effects of intracellular iron on XOR expression. Ferric ammonium citrate and FeSO(4) elevated intracellular iron levels and increased XOR activity ...

Expression and Regulation of Human Xanthine Oxidoreductase

Yliopistopaino The truth is rarely pure and never simple.