title: Essentiality of Glu-48 of ribulose bisphosphate carboxylase/oxygenase as demonstrated by site-directed mutagenesis.
abstract: Previous reports provide indirect evidence for the presence of Glu-48 at the active site of ribulose bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum. This possibility has been examined directly by replacement of Glu-48 with glutamine via site-directed mutagenesis. This single amino acid substitution does not prevent subunit association or ligand binding. However, the Glu-48 mutant is severely deficient in catalytic activity, exhibiting a kcat only 0.05% that of wild-type enzyme. These results demonstrate that Glu-48 is positioned at the active site and suggest that it serves a functional role. In conjunction with previous studies, the discovery of essentiality of Glu-48 argues that the active site is located at an interface between subunits.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics; D005796:Genes; D005971:Glutamates; D018698:Glutamic Acid; D009154:Mutation; D012247:Rhodospirillum rubrum / Q000201:enzymology* / Q000235:genetics; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics* / Q000378:metabolism
chemical_list: D005971:Glutamates; D018698:Glutamic Acid; D012273:Ribulose-Bisphosphate Carboxylase