Ligase Chain Reaction
odonnell at sasa.gov.uk
Mon Mar 27 04:21:42 EST 1995
In article <3kvmqt$l1a at deep.rsoft.bc.ca>, Donald Lee
<don_lee at mindlink.bc.ca> says:
>Can anyone be kind enough to explain what is a Ligase Chain Reaction?
>Be technical if you like. Just happened to be out of science for a few
>Thank you in advance.
I'll have a go.
LCR is a nucleic acid amplification method that uses 2 pairs of
complimentary probes. Probes 1 and 2 are designed to anneal to target
DNA immediately adjacent to one another. The 'nick' between them is
recognised by DNA ligase and ligated, so that 2 oligomers of e.g. 25 nt
become one 50nt oligo. The mixture is then heated so that the probe and
target DNA are separated. On cooling, further copies of probes 1&2
can anneal to the target and probes 3&4 can anneal to the ligation product
of probes 1&2, formed in the last round.
The use of a thermostable ligase means that you can go through succesive
round of denaturing/annealing/ligation. The end result is the exponential
generation of 50nt ligation products from 25 nt probes. The advantages to
this system are that it is sensitive to single base pair changes in the target
and that it has to potential for automated detection through labelling of the
Useful references are:
Barany, F. 1991 Genetic disease detection and DNA amplification using
cloned thermostable ligase Proc. Nat. Acad. Sci. 88:189-193
(the original LCR paper)
and a recent review:
Wiedmann et al. 1994 ligase chain reaction (LCR) -overview and
applications PCR Methods and Applications 3:S51-S64
Hope this is helpful - it's a lot clearer when you've got a diagram in front
Scottish Agricultural Science Agency
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