Endonucleases

From The School of Biomedical Sciences Wiki
Jump to: navigation, search

A class of nuclease which hydrolyses the middle of the polynucleotide chain of a nucleic acid[1], by cleavage of the phosphodiester bond. Endonucleases can be non-specific (cleaving indiscriminately along the polynucleotide) or they can be specific, cutting at certain sites which are recognised by the enzyme; these are called restriction endonucleases[2]

Endonucleases usually recognise palnidromic sequences in DNA to ensure that both strands of dsDNA are cleaved[3]. Some restriction endonuclease enzymes will cut the DNA to give blunt ends, whereas other restriction endonuclease enzymes will cut the DNA to produce sticky ends. The production of sticky ends is due to staggered cutting of the DNA sequence. Sticky ends are 5' or 3' overhangs in the DNA sequence. Sticky ends are important in recombinant DNA technology to allow complemetary base pairing and hydrogen bonds to form between plasmid DNA and a fragment of DNA[4].

Restriction endonuclease enzymes are naturally produced by bacteria as a defence mechanism against bacteriophages. The enzyme will cleave viral nucleic acid, therefore it can not be transcribed and replicated so no new viral particles can be synthesised inside of the host cell[5]

References

  1. Alberts B [et al] (2008) Molecular Biology of the Cell, Fifth Edition, New York:Garland Science
  2. Cox M, Nelson DR, Lehninger AL (2005). Lehninger principles of biochemistry. San Francisco: W.H. Freeman. p. 952.
  3. Smith DR1. Restriction endonuclease digestion of DNA. Methods Mol Biol. 1993;18:427-31.
  4. Griffiths AJF, Miller JH, Suzuki DT, et al. An Introduction to Genetic Analysis. 7th edition. New York: W. H. Freeman; 2000.
  5. Griffiths AJF, Miller JH, Suzuki DT, et al.fckLRAn Introduction to Genetic Analysis. 7th edition. New York: W. H. Freeman; 2000.
Personal tools
Namespaces
Variants
Actions
Navigation
Toolbox