Restriction enzyme: Difference between revisions
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=== Type II === |
=== Type II === |
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[[Image:1QPS.png|thumb|right|Structure of the [[dimer|homodimeric]] restriction enzyme [[EcoRI]] (cyan and green cartoon diagram) bound to double stranded [[DNA]] (brown tubes) based |
[[Image:1QPS.png|thumb|260px|right|Structure of the [[dimer|homodimeric]] restriction enzyme [[EcoRI]] (cyan and green cartoon diagram) bound to double stranded [[DNA]] (brown tubes) based on the {{PDB|1qps}} coordinates. Two catalytic [[manganese]] ions (one from each [[monomer]]) are shown as magenta spheres and are adjacent to the cleaved sites in the DNA made by the enzyme (depicted as gaps in the DNA backbone).]] |
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Typical type II restriction enzymes differ from type I restriction enzymes in several ways. They are composed of only one subunit, their recognition sites are usually undivided and palindromic and 4-8 nucleotides in length, they recognize and cleave DNA at the same site, and they do not use ATP or AdoMet for their activity – they usually require only Mg<sup>2+</sup> as a cofactor.<ref name="pmid11557805">{{cite journal | author = Pingoud A, Jeltsch A | title = Structure and function of type II restriction endonucleases | journal = Nucleic Acids Res. | volume = 29 | issue = 18 | pages = 3705–27 | year = 2001 | month = September | pmid = 11557805 | pmc = 55916 | doi = 10.1093/nar/29.18.3705 | url = }}</ref> These are the most commonly available and used restriction enzymes. In the 1990s and early 2000s, new enzymes from this family were discovered that did not follow all the classical criteria of this enzyme class, and new subfamily [[nomenclature]] was developed to divide this large family into subcategories based on deviations from typical characteristics of type II enzymes.<ref name="pmid11557805"/> These subgroups are defined using a letter suffix. |
Typical type II restriction enzymes differ from type I restriction enzymes in several ways. They are composed of only one subunit, their recognition sites are usually undivided and palindromic and 4-8 nucleotides in length, they recognize and cleave DNA at the same site, and they do not use ATP or AdoMet for their activity – they usually require only Mg<sup>2+</sup> as a cofactor.<ref name="pmid11557805">{{cite journal | author = Pingoud A, Jeltsch A | title = Structure and function of type II restriction endonucleases | journal = Nucleic Acids Res. | volume = 29 | issue = 18 | pages = 3705–27 | year = 2001 | month = September | pmid = 11557805 | pmc = 55916 | doi = 10.1093/nar/29.18.3705 | url = }}</ref> These are the most commonly available and used restriction enzymes. In the 1990s and early 2000s, new enzymes from this family were discovered that did not follow all the classical criteria of this enzyme class, and new subfamily [[nomenclature]] was developed to divide this large family into subcategories based on deviations from typical characteristics of type II enzymes.<ref name="pmid11557805"/> These subgroups are defined using a letter suffix. |
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Revision as of 20:22, 21 October 2008
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A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double-stranded DNA at specific recognition nucleotide sequences known as restriction sites.[1][2][3] Such enzymes, found in bacteria and archaea, are thought to have evolved to provide a defense mechanism against invading viruses.[4][5] Inside a bacterial host, the restriction enzymes selectively cut up foreign DNA in a process called restriction; host DNA is methylated by a modification enzyme (a methylase) to protect it from the restriction enzyme’s activity. Collectively, these two processes form the restriction modification system.[6] To cut the DNA, a restriction enzyme makes two incisions, once through each sugar-phosphate backbone (i.e. each strand) of the DNA double helix.
The Nobel Prize in Medicine was awarded, in 1978, to Daniel Nathans, Werner Arber, and Hamilton Smith for the discovery of restriction endonucleases.[7] Their discovery lead to the development of recombinant DNA technology that allowed, for example, the large scale production of human insulin for diabetics using E. coli bacteria.[8] Over 3000 restriction enzymes have been studied in detail, and more than 600 of these are available commercially[9] and are routinely used for DNA modification and manipulation in laboratories.[10][11][12]
Recognition site
5'-GTATAC-3' |
| A palindromic recognition site reads the same on the reverse strand as it does on the forward strand |
Restriction enzymes recognize a specific sequence of nucleotides[2] and produce a double-stranded cut in the DNA. While recognition sequences vary widely, with lengths between 4 and 8 nucleotides, many of them are palindromic; that is, the sequence on one strand reads the same in the reverse direction on the complementary strand.[13] The meaning of "palindromic" in this context is different from what one might expect from its linguistic usage: GTAATG is not a palindromic DNA sequence, but GTATAC is (GTATAC is complementary to CATATG).
 |
 |
| EcoRI digestion produces "sticky" ends | SmaI restriction enzyme cleavage produces "blunt" ends |
Recognition sequences in DNA differ for each restriction enzyme, producing differences in the length, sequence and strand orientation (5' end or the 3' end) of a sticky-end "overhang" of an enzyme restriction.[14]
Different restriction enzymes that recognize the same sequence are known as neoschizomers. These often cleave in a different locales of the sequence; however, the specific type that cleaves in the same location as the prototype is known as an isoschizomer.
Bacteria prevent their own DNA from being cut by modifying their nucleotides via DNA methylation.[4]
Restriction endonucleases are categorized into three general groups (Types I, II and III) based on their composition and enzyme cofactor requirements, the nature of their target sequence, and the position of their DNA cleavage site relative to the target sequence.[15][16][17]
Type I
Type I restriction enzymes were the first to be identified and are characteristic of two different strains (K-12 and B) of E. coli.[18] These enzymes cut at a site that differs, and is some distance (at least 1000 bp) away, from their recognition site. The recognition site is asymmetrical and is composed of two portions – one containing 3-4 nucleotides, and another containing 4-5 nucleotides – separated by a spacer of about 6-8 nucleotides. Several enzyme cofactors, including S-Adenosyl methionine (AdoMet), hydrolyzed adenosine triphosphate (ATP) and magnesium (Mg2+) ions, are required for their activity. Type I restriction enzymes possess three subunits called HsdR, HsdM, and HsdS; HsdR is required for restriction, HsdM is necessary for adding methyl groups to host DNA (methyltransferase activity) and HsdS is important for specificity of cut site recognition in addition to its methyltransferase activity.[15][18]
Type II
Typical type II restriction enzymes differ from type I restriction enzymes in several ways. They are composed of only one subunit, their recognition sites are usually undivided and palindromic and 4-8 nucleotides in length, they recognize and cleave DNA at the same site, and they do not use ATP or AdoMet for their activity – they usually require only Mg2+ as a cofactor.[13] These are the most commonly available and used restriction enzymes. In the 1990s and early 2000s, new enzymes from this family were discovered that did not follow all the classical criteria of this enzyme class, and new subfamily nomenclature was developed to divide this large family into subcategories based on deviations from typical characteristics of type II enzymes.[13] These subgroups are defined using a letter suffix.
Type IIB restriction enzymes (e.g. BcgI and BplI) are multimers, containing more than one subunit.[13] They cleave DNA on both sides of their recognition to cut out the recognition site. They require both AdoMet and Mg2+ cofactors. Type IIE restriction endonucleases (e.g. NaeI) cleave DNA following interaction with two copies of their recognition sequence.[13] One recognition site acts as the target for cleavage, while the other acts as an allosteric effector that speeds up or improves the efficiency of enzyme cleavage. Similar to type IIE enzymes, type IIF restriction endonucleases (e.g. NgoMIV) interact with two copies of their recognition sequence but cleave both sequences at the same time.[13] Type IIG restriction endonucleases (Eco57I) do have a single subunit, like classical Type II restriction enzymes, but require the cofactor AdoMet to be active.[13] Type IIM restriction endonucleases, such as DpnI, are able to recognize and cut methylated DNA.[13] Type IIS restriction endonucleases (e.g. FokI) cleave DNA at a defined distance from their non-palindromic asymmetric recognition sites.[13] These enzymes may function as dimers. Similarly, Type IIT restriction enzymes (e.g., Bpu10I and BslI) are composed of two different subunits. Some recognize palindromic sequences while others have asymmetric recognition sites.[13]
Type III
Type III restriction enzymes (e.g. EcoP15) recognize two separate non-palindromic sequences that are inversely oriented. They cut DNA about 20-30 base pairs after the recognition site.[19] These enzymes contain more than one subunit and require AdoMet and ATP cofactors for their roles in DNA methylation and restriction, respectively.[20]
Nomenclature
| E | Escherichia | (genus) |
| co | coli | (species) |
| R | RY13 | (strain) |
| I | First identified | (order of identification in the bacterium) |
Since their discovery in the 1970s, more than 100 different restriction enzymes have been identified in different bacteria. Each enzyme is named after the bacterium from which it was isolated using a naming system based on bacterial genus, species and strain.[21][22] For example, the name of the EcoRI restriction enzyme was derived as shown in the box.
Restriction enzymes as tools
- See the main article on restriction digests.
Isolated restriction enzymes are used to manipulate DNA for different scientific applications.
They are used to assist insertion of genes into plasmid vectors during gene cloning and protein expression experiments. For optimal use, plasmids that are commonly used for gene cloning are modified to include a short linker sequence (called the multiple cloning site, or MCS) rich in restriction enzyme recognition sequences. This allows flexibility when inserting gene fragments into the plasmid vector; restriction sites contained naturally within genes influence the choice of endonuclease for digesting the DNA since it is necessary to avoid restriction of wanted DNA while intentionally cutting the ends of the DNA. To clone a gene fragment into a vector, both plasmid DNA and gene insert are typically cut with the same restriction enzymes, and then glued together with the assistance of an enzyme known as a DNA ligase.[23][24]
Restriction enzymes can also be used to distinguish gene alleles by specifically recognizing single base changes in DNA known as single nucleotide polymorphisms (SNPs).[25][26] This is only possible if a SNP alters the restriction site present in the allele. In this method, the restriction enzyme can be used to genotype a DNA sample without the need for expensive gene sequencing. The sample is first digested with the restriction enzyme to generate DNA fragments, and then the different sized fragments separated by gel electrophoresis. In general, alleles with correct restriction sites will generate two visible bands of DNA on the gel, and those with altered restriction sites will not be cut and will generate only a single band. The number of bands reveals the sample subject's genotype, an example of restriction mapping.
In a similar manner, restriction enzymes are used to digest genomic DNA for gene analysis by Southern blot. This technique allows researchers to identify how many copies (or paralogues) of a gene are present in the genome of one individual, or how many gene mutations (polymorphisms) have occurred within a population. The latter example is called restriction fragment length polymorphism (RFLP).[27]
Examples
Examples of restriction enzymes include:[28]
| Enzyme | Source | Recognition Sequence | Cut |
|---|---|---|---|
| EcoRI | Escherichia coli |
5'GAATTC 3'CTTAAG |
5'---G AATTC---3' 3'---CTTAA G---5' |
| EcoRII | Escherichia coli |
5'CCWGG 3'GGWCC |
5'--- CCWGG---3' 3'---GGWCC ---5' |
| BamHI | Bacillus amyloliquefaciens |
5'GGATCC 3'CCTAGG |
5'---G GATCC---3' 3'---CCTAG G---5' |
| HindIII | Haemophilus influenzae |
5'AAGCTT 3'TTCGAA |
5'---A AGCTT---3' 3'---TTCGA A---5' |
| TaqI | Thermus aquaticus |
5'TCGA 3'AGCT |
5'---T CGA---3' 3'---AGC T---5' |
| NotI | Nocardia otitidis |
5'GCGGCCGC 3'CGCCGGCG |
5'---GC GGCCGC---3' 3'---CGCCGG CG---5' |
| HinfI | Haemophilus influenzae |
5'GANTC 3'CTNAG |
5'---G ANTC---3' 3'---CTNA G---5' |
| Sau3A | Staphylococcus aureus |
5'GATC 3'CTAG |
5'--- GATC---3' 3'---CTAG ---5' |
| PovII* | Proteus vulgaris |
5'CAGCTG 3'GTCGAC |
5'---CAG CTG---3' 3'---GTC GAC---5' |
| SmaI* | Serratia marcescens |
5'CCCGGG 3'GGGCCC |
5'---CCC GGG---3' 3'---GGG CCC---5' |
| HaeIII* | Haemophilus aegyptius |
5'GGCC 3'CCGG |
5'---GG CC---3' 3'---CC GG---5' |
| AluI* | Arthrobacter luteus |
5'AGCT 3'TCGA |
5'---AG CT---3' 3'---TC GA---5' |
| EcoRV* | Escherichia coli |
5'GATATC 3'CTATAG |
5'---GAT ATC---3' 3'---CTA TAG---5' |
| KpnI[29] | Klebsiella pneumoniae |
5'GGTACC 3'CCATGG |
5'---GGTAC C---3' 3'---C CATGG---5' |
| PstI[29] | Providencia stuartii |
5'CTGCAG 3'GACGTC |
5'---CTGCA G---3' 3'---G ACGTC---5' |
| SacI[29] | Streptomyces achromogenes |
5'GAGCTC 3'CTCGAG |
5'---GAGCT C---3' 3'---C TCGAG---5' |
| SalI[29] | Streptomyces albus |
5'GTCGAC 3'CAGCTG |
5'---G TCGAC---3' 3'---CAGCT G---5' |
| ScaI[29] | Streptomyces caespitosus |
5'AGTACT 3'TCATGA |
5'---AGT ACT---3' 3'---TCA TGA---5' |
| SphI[29] | Streptomyces phaeochromogenes |
5'GCATGC 3'CGTACG |
5'---G CATGC---3' 3'---CGTAC G---5' |
| StuI [30][31] | Streptomyces tubercidicus |
5'AGGCCT 3'TCCGGA |
5'---AGG CCT---3' 3'---TCC GGA---5' |
| XbaI[29] | Xanthomonas badrii |
5'TCTAGA 3'AGATCT |
5'---T CTAGA---3' 3'---AGATC T---5' |
| * = blunt ends | |||
| N = C or G or T or A | |||
| W = A or T | |||
See also
References
- ^ Roberts RJ (1976). "Restriction endonucleases". CRC Crit. Rev. Biochem. 4 (2): 123–64. PMID 795607.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ a b Kessler C, Manta V (1990). "Specificity of restriction endonucleases and DNA modification methyltransferases a review (Edition 3)". Gene. 92 (1–2): 1–248. doi:10.1016/0378-1119(90)90486-B. PMID 2172084.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Pingoud A, Alves J, Geiger R (1993). "Chapter 8: Restriction Enzymes". In Burrell, Michael (ed.). Enzymes of Molecular Biology. Methods of Molecular Biology. Vol. 16. Totowa, NJ: Humana Press. pp. pages 107-200. ISBN 0-89603-234-5.
{{cite book}}:|pages=has extra text (help)CS1 maint: multiple names: authors list (link) - ^ a b Arber W, Linn S (1969). "DNA modification and restriction". Annu. Rev. Biochem. 38: 467–500. doi:10.1146/annurev.bi.38.070169.002343. PMID 4897066.
- ^ Krüger DH, Bickle TA (1983). "Bacteriophage survival: multiple mechanisms for avoiding the deoxyribonucleic acid restriction systems of their hosts". Microbiol. Rev. 47 (3): 345–60. PMC 281580. PMID 6314109.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Kobayashi I (2001). "Behavior of restriction-modification systems as selfish mobile elements and their impact on genome evolution". Nucleic Acids Res. 29 (18): 3742–56. doi:10.1093/nar/29.18.3742. PMC 55917. PMID 11557807.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ "The Nobel Prize in Physiology or Medicine". The Nobel Foundation. 1978. Retrieved 2008-06-07.
for the discovery of restriction enzymes and their application to problems of molecular genetics
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ Villa-Komaroff L, Efstratiadis A, Broome S, Lomedico P, Tizard R, Naber SP, Chick WL, Gilbert W. (1978). "A bacterial clone synthesizing proinsulin". Proc. Natl. Acad. Sci. U.S.A. 75 (8): 3727–31. PMC 392859. PMID 358198.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Roberts RJ, Vincze T, Posfai J, Macelis D. (2007). "REBASE--enzymes and genes for DNA restriction and modification". Nucleic Acids Res. 35 (Database issue): D269-70. doi:10.1093/nar/gkl891. PMID 17202163.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Primrose, Sandy B.; Old, R. W. (1994). Principles of gene manipulation: an introduction to genetic engineering. Oxford: Blackwell Scientific. ISBN 0-632-03712-1.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Micklos, David A.; Bloom, Mark V.; Freyer, Greg A. (1996). Laboratory DNA science: an introduction to recombinant DNA techniques and methods of genome analysis. Menlo Park, Calif: Benjamin/Cummings Pub. Co. ISBN 0-8053-3040-2.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Adrianne Massey; Helen Kreuzer (2001). Recombinant DNA and Biotechnology: A Guide for Students. Washington, D.C: ASM Press. ISBN 1-55581-176-0.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e f g h i j Pingoud A, Jeltsch A (2001). "Structure and function of type II restriction endonucleases". Nucleic Acids Res. 29 (18): 3705–27. doi:10.1093/nar/29.18.3705. PMC 55916. PMID 11557805.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Goodsell DS (2002). "The molecular perspective: restriction endonucleases". Stem Cells. 20 (2): 190–1. PMID 11897876.
- ^ a b Bickle TA, Krüger DH (1993). "Biology of DNA restriction". Microbiol. Rev. 57 (2): 434–50. PMC 372918. PMID 8336674.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Boyer HW (1971). "DNA restriction and modification mechanisms in bacteria". Annu. Rev. Microbiol. 25: 153–76. doi:10.1146/annurev.mi.25.100171.001101. PMID 4949033.
- ^ Yuan R (1981). "Structure and mechanism of multifunctional restriction endonucleases". Annu. Rev. Biochem. 50: 285–319. doi:10.1146/annurev.bi.50.070181.001441. PMID 6267988.
- ^ a b Murray NE (2000). "Type I restriction systems: sophisticated molecular machines (a legacy of Bertani and Weigle)". Microbiol. Mol. Biol. Rev. 64 (2): 412–34. PMC 98998. PMID 10839821.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Dryden DT, Murray NE, Rao DN (2001). "Nucleoside triphosphate-dependent restriction enzymes". Nucleic Acids Res. 29 (18): 3728–41. doi:10.1093/nar/29.18.3728. PMC 55918. PMID 11557806.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Meisel A, Bickle TA, Krüger DH, Schroeder C (1992). "Type III restriction enzymes need two inversely oriented recognition sites for DNA cleavage". Nature. 355 (6359): 467–9. doi:10.1038/355467a0. PMID 1734285.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Smith HO, Nathans D (1973). "Letter: A suggested nomenclature for bacterial host modification and restriction systems and their enzymes". J. Mol. Biol. 81 (3): 419–23. PMID 4588280.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Roberts RJ, Belfort M, Bestor T, Bhagwat AS, Bickle TA, Bitinaite J, Blumenthal RM, Degtyarev SKh, Dryden DT, Dybvig K, Firman K, Gromova ES, Gumport RI, Halford SE, Hattman S, Heitman J, Hornby DP, Janulaitis A, Jeltsch A, Josephsen J, Kiss A, Klaenhammer TR, Kobayashi I, Kong H, Krüger DH, Lacks S, Marinus MG, Miyahara M, Morgan RD, Murray NE, Nagaraja V, Piekarowicz A, Pingoud A, Raleigh E, Rao DN, Reich N, Repin VE, Selker EU, Shaw PC, Stein DC, Stoddard BL, Szybalski W, Trautner TA, Van Etten JL, Vitor JM, Wilson GG, Xu SY (2003). "A nomenclature for restriction enzymes, DNA methyltransferases, homing endonucleases and their genes". Nucleic Acids Res. 31 (7): 1805–12. doi:10.1093/nar/gkg274. PMC 152790. PMID 12654995.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Geerlof A. "Cloning using restriction enzymes". European Molecular Biology Laboratory - Hamburg. Retrieved 2008-06-07.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ Russell, David W.; Sambrook, Joseph (2001). Molecular cloning: a laboratory manual. Cold Spring Harbor, N.Y: Cold Spring Harbor Laboratory. ISBN 0-87969-576-5.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Wolff JN, Gemmell NJ (2008). "Combining allele-specific fluorescent probes and restriction assay in real-time PCR to achieve SNP scoring beyond allele ratios of 1:1000". BioTechniques. 44 (2): 193–4, 196, 199. PMID 18330346.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ Zhang R, Zhu Z, Zhu H, Nguyen T, Yao F, Xia K, Liang D, Liu C (2005). "SNP Cutter: a comprehensive tool for SNP PCR-RFLP assay design". Nucleic Acids Res. 33 (Web Server issue): W489–92. doi:10.1093/nar/gki358. PMC 1160119. PMID 15980518.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ Stryer, Lubert; Berg, Jeremy Mark; Tymoczko, John L. (2002). Biochemistry (Fifth Edition ed.). San Francisco: W.H. Freeman. pp. page 122. ISBN 0-7167-4684-0.
{{cite book}}:|edition=has extra text (help);|pages=has extra text (help)CS1 maint: multiple names: authors list (link) - ^ Roberts RJ (1980). "Restriction and modification enzymes and their recognition sequences". Nucleic Acids Res. 8 (1): r63–r80. doi:10.1093/nar/8.1.197-d. PMC 327257. PMID 6243774.
{{cite journal}}: Unknown parameter|month=ignored (help) - ^ a b c d e f g Monty Krieger; Matthew P Scott; Matsudaira, Paul T.; Lodish, Harvey F.; Darnell, James E.; Lawrence Zipursky; Kaiser, Chris; Arnold Berk (2004). Molecular Cell Biology (5th ed ed.). New York: W.H. Freeman and Company. ISBN 0-7167-4366-3.
{{cite book}}:|edition=has extra text (help)CS1 maint: multiple names: authors list (link) - ^ "Stu I from Streptomyces tubercidicus". Sigma-Aldrich. Retrieved 2008-06-07.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - ^ Shimotsu H, Takahashi H, Saito H (1980). "A new site-specific endonuclease StuI from Streptomyces tubercidicus". Gene. 11 (3–4): 219–25. doi:10.1016/0378-1119(80)90062-1. PMID 6260571.
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External links
General:
- DNA Restriction Enzymes at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Firman K (2007-11-24). "Type I Restriction-Modification". University of Portsmouth. Retrieved 2008-06-06.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - Goodsell DS (2000-08-01). "Restriction Enzymes". Molecule of the Month. RCSB Protein Data Bank. Retrieved 2008-06-06.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - Simmer M, Secko D (2003-08-01). "Restriction Endonucleases: Molecular Scissors for Specifically Cutting DNA". The Science Creative Quarterly. Retrieved 2008-06-06.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help)
Databases:
- Roberts RJ, Vincze T, Posfai, J, Macelis D. "REBASE". Retrieved 2008-06-06.
Restriction Enzyme Database
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help)CS1 maint: multiple names: authors list (link)
Software:
- Bikandi J, San Millán R, Rementeria A, and Garaizar J. "Restriction enzyme digest of DNA". insilico.ehu.es. Retrieved 2008-06-06.
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help)CS1 maint: multiple names: authors list (link) - Palmer M. "WatCut". University of Waterloo, Ontario, Canada. Retrieved 2008-06-06.
An on-line tool for restriction analysis, silent mutation scanning, SNP-RFLP analysis
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - Vincze,T, Posfai J, Roberts RJ. "NEBcutter V2.0". New England Biolabs Inc. Retrieved 2008-06-06.
Restriction enzyme finder
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help)CS1 maint: multiple names: authors list (link) - "Restriction enzyme digest of DNA software". BioPHP: PHP for Bioinformatics. Retrieved 2008-06-06.
Online tool, free source code
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help) - "pDRAW32". AcaClone software. Retrieved 2008-06-06.
Freeware DNA cloning, sequence analysis and plasmid/DNA plotting software
{{cite web}}: Cite has empty unknown parameter:|coauthors=(help)