Words similar to topoisomerase
Example sentences for: topoisomerase
How can you use “topoisomerase” in a sentence? Here are some example sentences to help you improve your vocabulary:
There are two homologous type IA topoisomerases present in E. coli . Topoisomerase III has potent DNA decatenating activity for resolution of plasmid DNA replication intermediates, but much weaker relaxation activity than topoisomerase I [ 17 ] . To exhibit maximal relaxation activity, topoisomerase III requires high temperature (52°C) along with low magnesium and monovalent ion [ 17 18 ] . In contrast, E. coli topoisomerase I was not active in the in vitro assay for resolution of plasmid DNA replication intermediates [ 19 ] . Removal of the C-terminal 49 amino acids from the 653 amino acid topoisomerase III protein resulted in drastic reduction of catalytic activity [ 20 ] . Fusion of the carboxyl-terminal 312 amino acid residues of E. coli topoisomerase I, which includes the entire ZD domain, onto the 605 N-terminal amino acids of topoisomerase III generated a hybrid topoisomerase that has relaxation activity resembling topoisomerase III along with weak decatenating activity [ 21 ] . Although preferring single-stranded DNA as binding substrate, topoisomerase I had been shown to also bind double-stranded DNA [ 22 ] , but there is no data available to indicate which domain in the enzyme is responsible for this interaction.
Finally, the in vivo catalytic activities of eukarytotic type IA topoisomerases, the topoisomerase III from various higher organisms may be related to their sequences.
This hypothesis could be tested using other DNA topoisomerase poisons known to induce NF-κB [ 34].
Removal of negative supercoils from DNA by bacterial type IA topoisomerase involves the following steps: (1) binding of the enzyme to the junction of double-stranded and single-stranded DNA [ 8 ] ; (2) cleavage of a single-strand of DNA near the junction with cleavage sequence preference of a cytosine in the -4 position to form the covalent intermediate [ 9 10 ] ; (3) conformational change of the covalent enzyme-DNA complex to result in physical separation of the 5' phosphate covalently linked to the active tyrosine, and the 3' hydroxyl of the cleaved DNA; (4) passage of the complementary single strand through the break; (5) enzyme conformational change to bring the 5' phosphoryl end back into the proximity of the 3' hydroxyl group of the cleaved DNA; (6) religation of the phosphodiester bond.
Escherichia coli DNA topoisomerase I is a representative example of type IA DNA topoisomerase (for reviews, see refs [ 1 2 ] ). Its major biological role in the bacterial cell is the removal of excessive negative supercoils from DNA to maintain the DNA at optimal superhelical density along with DNA gyrase [ 3 ] . The enzyme has a molecular weight of 97 kDa and the active site tyrosine responsible for DNA cleavage is found in the 67 kDa N-terminal transesterification domain.