Nick translation

Nick translation of a DNA labeling technique is known in molecular biology. In this case, one takes advantage of the repair function of the DNA polymerase I from Escherichia coli, in order to incorporate labeled nucleotides in single-strand breaks, so-called nick.

The DNA polymerase I is an enzyme that single-strand breaks or single-strand gaps in the DNA that can interfere with transcription or by mechanical stress can even lead to demolition of the DNA molecule, repair. For this, the polymerase having a 5 '→ 3' exonuclease activity, wherein the nucleotides are removed from the 5 ' end in the direction of 3' end. This exonuclease activity is a feature of DNA polymerase I. It is not to be confused with the 3 '→ 5' exonuclease activity for proofreading which the DNA polymerase I has also. Strand breakage is not closed ( this is a DNA ligase required), but shifted. Hence the name nick translation.

Is specified as the substrate radioactive ( 3H, α - 32P ) or by a small molecule ( digoxigenin, biotin, fluorescent dye ) added labeled nucleotides, they are incorporated and highlight an area of the DNA strand. The marking intensity depends on the number of strand breaks and this is determined by the concentration of DNase I added to a given, which causes the nicks. Detection of the label depends on the marker. Detection is carried out, for example, through a fluorescence microscope or blotting techniques.

This coding system was developed in 1977 by Peter Rigby and colleagues.