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5.6.2.1: DNA topoisomerase

This is an abbreviated version!
For detailed information about DNA topoisomerase, go to the full flat file.

Word Map on EC 5.6.2.1

Reaction

ATP-independent breakage of single-stranded DNA, followed by passage and rejoining =

Synonyms

ATP-independent type I topoisomerase, AtTop1, bcTopo I, bcTopo IIIbeta, bi-subunit topoisomerase I, Bi-subunit topoisomerase IB, Ca-Top1, CrTop1, Dam DNA topoisomerase III, Deoxiribonucleate topoisomerase, Deoxiribonucleic topoisomerase, DNA Top IB, DNA topo I, DNA topoisomerase, DNA topoisomerase 1, DNA topoisomerase I, DNA topoisomerase I alpha, DNA topoisomerase I-B, DNA topoisomerase IB, DNA topoisomerase III, DNA topoisomerase IIIalpha, DNA topoisomerase type I, EC 5.99.1.2, EcTOP, ETOP, HssTopoI, HsTop1, hTop1p, hTopI, hTopo, htopo I, hTopo IIIalpha, hTopoI, human DNA topoisomerase I, human Top1, human topo I, human topoisomerase I, Isomerase, deoxiribonucleate topo-, Late protein H6, LdTop1, LdTOP1L, LdTOP1LS, LdTOP1S, LdTopIIIbeta, MimiTopIB, MsTopA, MtbTopA, mTopoI, MtTOP1, MttopoI, Nicking-closing enzyme, OjTop1, OlTop1, omega-Protein, OpTop1, PfTopI, PfTopoI, Poxviridae topoisomerase IB, Relaxing enzyme, Reverse gyrase, SiRe_1176, SsTop3, Swivelase, top I, Top1, TOP1alpha, TOP1mt, Top1p, TopA, TopI, TopIB, topo 1, Topo I, topo IB, topo V, topoI, Topoisomerase, topoisomerase 1, topoisomerase 1alpha, Topoisomerase I, topoisomerase I homolog, topoisomerase IB, topoisomerase III, topoisomerase IIIalpha, topoisomerase IIIbeta, topoisomerase IV, topoisomerase V, topoisomerase-I, topoIV, TopR1, TpI, Type I DNA topoisomerase, type I topoisomerase, type IA DNA topoisomerase, type IA topoisomerase, type IB topoisomerase, type IB topoisomerase V, Untwisting enzyme, Vaccinia DNA topoisomerase I, variola topoisomerase IB, vTopo, yeast DNA topoisomerase I, yeastTop1, YpTOP, YrdD, YTOP

ECTree

     5 Isomerases
         5.6 Isomerases altering macromolecular conformation
             5.6.2 Enzymes altering nucleic acid conformation
                5.6.2.1 DNA topoisomerase

pH Range

pH Range on EC 5.6.2.1 - DNA topoisomerase

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pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
5 - 8
-
pH 5: 25% of maximal activity, pH 6: about 50% of maximal activity, pH 8: about 50% of maximal activity
5.4 - 8.5
-
active in this range
5.5 - 8
solved crystal structures of wild-type Escherichia coli topoisomerase III bind to an eight-base ssDNA molecule in three different pH environments. A low pH of the crystallization environment (pH 5.5) inhibits the wild-type enzyme from cleaving its substrate. At pH 7.0, the overall conformation of each molecule in the asymmetric unit remains the same as that observed at pH 5.5. In the pH 8 structure, one of the molecules is in the open conformation and the other in the intermediate conformation, but no cleavage is observed. In all, there are seven different closed structures: one of the molecules in the asymmetric unit in each of the five different conditions (Form I pH 5.5 and 7.0 and Form II pH 5.5, 7.0, and 8.0), and two additional closed complexes in the glucose or Form I crystals. At a pH below 8, crystals cryo-protected with glycerol show one monomer in the closed conformation and one in the open conformation
5.5 - 9
-
relaxes DNA over a broad pH range
5.5 - 9.5
6 - 11
activity range at 37°C, inactive below pH 5.0
6 - 9.5
-
cleavage rates of both LdTOPIL-fus-S and the H453Q mutant LdTOPIL-fus-S proteins at the following pH values: 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, and 9.5 measured. Effect of pH on suicide cleavage rate for LdTOPIL-fus-S and H632Q mutants of LdTOPIL-fus-S proteins
6.5 - 10.4
bcTopo IIIbeta relaxes supercoiled DNA in a pH dependent manner. Distributive patterns of partially relaxed topoisomers appear with an increase of pH. Comparison with ecTopo III Escherichia coli topoisomerase characteristics