title: Purification and characterization of the aspartate chemoreceptor.
abstract: The chemoreceptor for aspartate in Salmonella typhimurium was purified from an Escherichia coli strain containing a plasmid bearing the receptor's structural gene (tar). The receptor was solubilized from salt-washed membranes with the nonionic detergent octyl-beta-D-glucopyranoside and purified by a combination of ion exchange, molecular sieve and hydroxyapatite-agarose chromatography. The inclusion of glycerol and 1,10-phenanthroline in all buffers used prior to ion exchange chromatography prevented scission of the receptor by an endogenous proteolytic activity. The solubilized receptor was estimated to have a molecular weight of 248,000 from its behavior on Sephacryl S-300, suggesting that the receptor may be organized as a multimer containing 4 +/- 1 identical subunits. Circular dichroic measurements of the purified protein indicate that 78% of its residues are arranged in helical secondary structures.
mesh_terms: D001426:Bacterial Proteins; D002628:Chemoreceptor Cells / Q000032:analysis; D002942:Circular Dichroism; D004926:Escherichia coli / Q000032:analysis; D008970:Molecular Weight; D011487:Protein Conformation; D017459:Receptors, Amino Acid; D017981:Receptors, Neurotransmitter / Q000032:analysis / Q000302:isolation & purification*
chemical_list: D001426:Bacterial Proteins; D017459:Receptors, Amino Acid; D017981:Receptors, Neurotransmitter; C031959:aspartic acid receptor