| Abstract: | An investigation into some of the properties of the two partially purified ornithine transcarbamylases of Escherichia coli K12 and that of Aeromonas proteolytica was conducted. The question of gene duplication in E. coli K12 was examined along with the taxonomic controversy of whether A. proteolytica should be placed among the Pseudomonadaceae or the Enterobacteriaceae. Basic enzymatic properties of the ornithine transcarbamylases were used to attempt to answer both questions. The two genes encoding ornithine transcarbamylase in E. coli K12, argF and argI, were independently transferred to an argI⁻ Salmonella typhimurium, a genus known to contain only the argI genetic locus, by episomal (F') conjugation. Isolation was from recipient cells that were mutagen-treated in order to enhance enzyme production. The argF-encoded ornithine transcarbamylase was heat treated at 55° for 5 min, precipitated by ammonium sulfate fractionation, followed by ion exchange chromatography on DEAE Sephadex A-50, and Sephadex G-150 gel chromatography. The argI enzyme was heat treated for 5 min at 55°, followed by ion exchange chromatography on DEAE Sephadex A-50 and Sephadex G-150 gel chromatography. ... |
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