Histidinol dehydrogenase from salmonella typhimurium and Escherichia coli. Purification, some characteristics and the amino acid sequence around a reactive thiol group.

The purification and some physical properties of histidinol dehydrogenase, L-histidinol-nicotinamide adenine dinucleotide oxido-reductase (EC 1.1.1.23) from either Salmonella typhimurium or Escherichia coli are reported in this paper. Modification of histidinol dehydrogenase with one equivalent of N-(4-dimethylamino-3,5-dinitrophenyl)maleimide at pH 6.8 yields an enzyme that is inactive toward the oxidation of L-histidinol. The modified cysteine residue was located in an acid insoluble tryptic core. The amino acid sequence around the reactive thiol group in S. typhimurium is: Leu-Cys-Gly-Val-Glu-Glu-Ile-Phe, and in E. coli is: Leu-Cys-Gly-Val-Glu-Asp-Val-Phe. These unique sequences show no homology to the reactive thiol groups from some other dehydrogenases.