Changes induced by oxygen in rat liver proteins identified by high-resolution two-dimensional gel electrophoresis

Molecular oxygen (O-2) regulates the expression of a variety of genes. Seve ral of the proteins that respond to changes in oxygen concentration have be en identified in a variety of cell lines. We extend these previous studies by analyzing the effect of oxygen on the entire protein expression profile of an intact organ using high-resolution two-dimensional gel electrophoresi s. To this end, we used an isolated, in vitro perfused organ preparation to produce two groups of rat livers perfused with high (95% O-2, 5% CO2) or l ow (95% N-2, 5% CO2) oxygen concentrations. Using two-dimensional gel elect rophoresis we compared the protein expression profiles of both groups of li vers. Computer analysis of the files obtained after laser densitometry of t he two-dimensional gels revealed two spots that were strongly up-regulated in high PO2 perfused livers compared with low PO2 perfused livers. These sp ots were analyzed by peptide mass fingerprinting analysis. These spots were identified as arginase 1 (liver-type arginase; EC 3.5.3.1) and mitochondri al enoyl-CoA hydratase 1 (EC 4.2.1.17). The possible role of these proteins in its new context of oxygen availability is discussed.