| host restriction-modification | A bacterial system where the bacterium is able to destroy invading DNA from a bacteriophage (virus which infects bacteria) while at the same time preventing the destruction of their own DNA. The phage DNA is cleaved by a restriction enzyme made by the bacterium, the bacterial DNA is modified (usually with methylation) so that the enzyme will not destroy it. (09 Oct 1997) |
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| DNA restriction enzymes | <enzyme> Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of dnas, and have made it possible to splice and recombine genes from one organism into the genome of another. Registry number: EC 3.1.21 (12 Dec 1998) |
| DNA restriction-modification enzymes | Systems consisting of two enzymes, a modification methylase and a restriction endonuclease. They are closely related in their specificity and protect the DNA of a given bacterial species. The methylase adds methyl groups to adenine or cytosine residues in the same target sequence that constitutes the restriction enzyme binding site. The methylation renders the target site resistant to restriction, thereby protecting DNA against cleavage. (12 Dec 1998) |
| ecori restriction enzyme | <enzyme, molecular biology> A commonly-used restriction enzyme (enzyme which will cleave the phosphodiester bonds of DNA at specific nucleotide sequences) that came from the bacteria Escherichia coli and recognises the sequence GAATTC. The enzyme will make a staggered cut of the double-stranded DNA molecule by cutting between the G and A on both strands. (09 Oct 1997) |
| lactase restriction | An inherited trait in which there is low lactase activity and thus there is defective lactose intestinal metabolism. Compare: lactase persistence. (05 Mar 2000) |
| aI1 endonuclease | <enzyme> Encoded by intron ai1 from saccharomyces cerevisiae Registry number: EC 2.7.7.- (26 Jun 1999) |
| bovine mitochondrial endonuclease | <enzyme> Dimer of 29kda peptide; prefers a conserved sequence in the displacement loop region of mitochondrial DNA; nicks double-stranded DNA and fragments single-stranded DNA Registry number: EC 3.1.21.- (26 Jun 1999) |
| Cap(m(7)GpppXm) endonuclease | <enzyme> Cleaves capped rnas to generate primers that initiate viral RNA transcription Registry number: EC 3.1.27.- Synonym: cap mgx endonuclease, decapping enzyme (26 Jun 1999) |
| VDE endonuclease | <enzyme> From saccharomyces cerevisiae; recognises an extended sequence 5'-tatsyatgyygggtgy/ggrgaarkmgkkaawgaaawg-3'; involved in nucleic acid rearrangements Registry number: EC 3.1.22.- Synonym: vma1 gene product, pi-scei endonuclease, vma1 protozyme (26 Jun 1999) |
| vsr endonuclease | <enzyme> From E coli, nicks double-stranded DNA which has been damaged to have thymidine residues mismatched to 2'-deoxyguanosine thus initiating vsp mismatch repair Registry number: EC 3.1.21.- (26 Jun 1999) |
| mitochondrial oxidative damage endonuclease | <enzyme> An 8-oxog-specific DNA endonuclease from rat liver mitochondria; recognises and incises at 8-oxog and abasic acid sites in duplex DNA Registry number: EC 3.1.25.- Synonym: oxidative damage-specific endonuclease, mtode enzyme (26 Jun 1999) |
| SanDI endonuclease | <enzyme> A type-ii restriction endonuclease; isolated from streptomyces; recognises the internally degenerate heptanucleotide sequence 5'-gggwccc-3' Registry number: EC 3.1.21.- Synonym: sandi enase (26 Jun 1999) |
| Schizosaccharomyces pombe DNA endonuclease | <enzyme> Cleaves the phosphodiester bond immediately 5' of either cyclobutane pyrimidine dimers or 6-4 pyrimidine pyrimidones of uv-damaged DNA Registry number: EC 3.1.25.- Synonym: uv damage endonuclease, s. Pombe DNA endonuclease, uve1 gene product, spde (26 Jun 1999) |
| SegE endonuclease | <enzyme> Site-specific endonuclease from phage t4; similar to i-tevi endonuclease Registry number: EC 3.1.25.- (26 Jun 1999) |
| spleen endonuclease | micrococcal endonuclease |