A rare-cutter enzyme is a restriction enzyme with a recognition sequence which occurs only rarely in a genome. An example is NotI, which cuts after the first GC of a 5'-GCGGCCGC-3' sequence; restriction enzymes with seven and eight base pair recognition sequences are often also called rare-cutter enzymes (six bp recognition sequences are much more common).

For example, rare-cutter enzymes with 7-nucleotide recognition sites cut once every 4⁷ bp (16,384 bp), and those with 8-nucleotide recognition sites cut every 4⁸ bp (65,536 bp) respectively. They are used in top-down mapping to cut a chromosome into chunks of these sizes on average.

External links

• Bio-Medicine.com's definition
• Veselkov AG, Demidov VV, Nielson PE, Frank-Kamenetskii MD (July 1996). "A new class of genome rare cutters". Nucleic Acids Res. 24 (13): 2483–7. doi:10.1093/nar/24.13.2483. PMC 145980. PMID 8692685.
• T.A. Brown (2006). Genomes (3rd ed.). Garland Science. ISBN 0815341385.