Cells have evolved DNA repair pathways that are dedicated to the maintenance of DNA integrity. In such pathways, damaged DNA is excised and the resulting gap is filled by DNA polymerase. Human DNA ligases, ligase I, III, and IV, utilize ATP as a co-factor in DNA joining reactions required for base excision and single strand break repair pathways. All DNA ligases contain an RFPR sequence and an active site motif (ASM) on each side of their catalytic domain. The RFPR is required for transfer of an AMP group from the enzyme to the 5'-phosphate terminus of a DNA nick. In addition, DNA ligase III has an N-terminal zinc finger domain (ZFD) that is homoloqous with the zinc fingers found in poly(ADP-ribose) polymerase (PARP). This domain is not required for DNA ligase activity, but enables DNA ligase III to interact with single strand gaps and single strand flaps. During base excision repair (BER), ATP-dependent ligation requires PARP, DNA polymerase β, and DNA ligase III interaction with XRCC1 within the BER complex. Thus, DNA ligase III may contain unique protein sequences that allow interaction and repair of specific types of DNA damage.
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注意事项:
1.Since applications vary, each investigator should titrate the reagent to obtain optimal results.
2.Caution: Sodium azide yields highly toxic hydrazoic acid under acidic conditions. Dilute azide compounds in running water before discarding to avoid accumulation of potentially explosive deposits in plumbing.