title: DNA gyrase: purification and catalytic properties of a fragment of gyrase B protein.
abstract: A protein isolated from Escherichia coli complements the DNA gyrase A (NalA) protein to generate an activity that relaxes supercoiled DNA. Oxolinic acid, a known inhibitor of DNA gyrase, blocks this activity and causes double-strand cleavage of DNA at the same sites as are attacked by DNA gyrase. The protein, of molecular weight 50,000, appears to be fragment of the DNA gyrase B (Cou) protein (molecular weight, 90,000) as judged by the identical sizes of numerous peptides produced by partial proteolytic digestion. The complex of this fragment and the gyrase A protein lacks both the DNA-supercoiling and DNA-dependent ATPase activities of DNA gyrase.
mesh_terms: D002384:Catalysis; D004250:DNA Topoisomerases, Type II / Q000302:isolation & purification / Q000378:metabolism*; D004278:DNA, Superhelical / Q000494:pharmacology; D004720:Endonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D046911:Macromolecular Substances; D008970:Molecular Weight; D010093:Oxolinic Acid / Q000494:pharmacology; D059005:Topoisomerase II Inhibitors
chemical_list: D004278:DNA, Superhelical; D046911:Macromolecular Substances; D059005:Topoisomerase II Inhibitors; D004720:Endonucleases; D004250:DNA Topoisomerases, Type II; D010093:Oxolinic Acid