Molecular forms and thermal and kinetic properties of purified glutathione reductase from two populations of barnyard grass (<i>Echinochloa crus-galli</i> (L.) Beauv.: Poaceae) from contrasting climatic regions in North America

Abstract

The thermal, kinetic, and electrophoretic properties of purified glutathione reductase (GR; EC 1.6.4.2) were analyzed in plants from two ecotypes of barnyard grass (Echinochloa crus-galli (L.) Beauv.: Poaceae) originating from sites of contrasting climates in Quebec (QUE) and Mississippi (MISS). Crude and purified GR preparations from plants of both ecotypes consisted of one homodimer isomorph with the same electrophoretic mobility in polyacrylamide gels, a similar molecular mass for the native enzyme (98 kDa) and for each subunit of the dimer (44 kDa), and an identical pI of 5.9. The electrophoretic profile of GR purified from cold-acclimated plants at 14°C light (L) : 8°C dark (D) for 10 days was similar to that of GR from plants grown at 26°C L : 20°C D. Specific activities of purified GR from QUE plants were significantly higher than those of MISS plants. In vitro GR activities from QUE and MISS plants were not differentially affected by thermodenaturation at 55 or 65°C or by cold treatments at 2°C. A...