title: A cyanogen bromide fragment of beta-galactosidase from Escherichia coli with alpha-donor activity in complementation of the enzyme from mutant M15.
abstract: Aminoethylated beta-galactosidase from Escherichia coli was cleaved by CNBr. The fragment C4a was purified by gel filtration and ion-exchange chromatography. The molecular weight of the fragment C4a was determined to be 9000 +/- 600. The N-terminal amino acid was found to be isoleucine. Qualitative examination of homogeneity was carried out by disc-gel electrophoresis. The fragment C4a was shown to be active as an alpha donor in complementation of beta-galactosidase activity in vitro with E. coli mutant M15, which has a deletion in the alpha region of the z gene. The molecular weights of complementable fractions from mutant M15 were found to be 123 000 +/- 2500 and 507 000 +/- 11 000, and of the complemented enzyme 522 500 +/- 11 400.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000645:Ammonium Sulfate; D003488:Cyanogen Bromide; D004789:Enzyme Activation; D004926:Escherichia coli / Q000201:enzymology*; D005696:Galactosidases / Q000032:analysis* / Q000378:metabolism; D005816:Genetic Complementation Test; D007532:Isoleucine / Q000032:analysis; D008954:Models, Biological; D008970:Molecular Weight; D009154:Mutation; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D007532:Isoleucine; D005696:Galactosidases; D003488:Cyanogen Bromide; D000645:Ammonium Sulfate