| 词条 | Micrococcal nuclease |
| 释义 |
| Name = Micrococcal nuclease | EC_number = 3.1.31.1 | CAS_number = 9013-53-0 | IUBMB_EC_number = 3/1/31/1 | GO_code = | image = Staph nuclease 3h6m ribbon.jpg | width = | caption = Ribbon schematic of micrococcal nuclease 3D structure, with Ca2+ and TdtP inhibitor }} Micrococcal nuclease ({{EC number|3.1.31.1}}, S7 Nuclease, MNase, spleen endonuclease, thermonuclease, nuclease T, micrococcal endonuclease, nuclease T', staphylococcal nuclease, spleen phosphodiesterase, Staphylococcus aureus nuclease, Staphylococcus aureus nuclease B, ribonucleate (deoxynucleate) 3'-nucleotidohydrolase) is an endo-exonuclease that preferentially digests single-stranded nucleic acids. The rate of cleavage is 30 times greater at the 5' side of A or T than at G or C and results in the production of mononucleotides and oligonucleotides with terminal 3'-phosphates. The enzyme is also active against double-stranded DNA and RNA and all sequences will be ultimately cleaved. CharacteristicsThe enzyme has a molecular weight of 16.9kDa. The pH optimum is reported as 9.2. The enzyme activity is strictly dependent on Ca2+ and the pH optimum varies according to Ca2+ concentration.[1] The enzyme is therefore easily inactivated by EGTA. SourcesThis enzyme is the extracellular nuclease of Staphylococcus aureus. Two strains, V8 and Foggi, yield almost identical enzymes.[2] A common source is E.coli cells carrying a cloned nuc gene encoding Staphylococcus aureus extracellular nuclease (micrococcal nuclease). StructureThe 3-dimensional structure of micrococcal nuclease (then called Staphyloccal nuclease) was solved very early in the history of protein crystallography, in 1969,[3] deposited as now-obsolete Protein Data Bank file 1SNS. Higher-resolution, more recent crystal structures are available for the apo form as Protein Data Bank file 1SNO: and for the thymidine-diphosphate-inhibited form as Protein Data Bank file 3H6M: or 1SNC: . As seen in the ribbon diagram above, the nuclease molecule has 3 long alpha helices and a 5-stranded, barrel-shaped beta sheet, in an arrangement known as the OB-fold (for oligonucleotide-binding fold) as classified in the SCOP database. Applications
References1. ^{{cite journal |vauthors=Heins JN, Suriano JR, Taniuchi H, Anfinsen CB |title=Characterization of a nuclease produced by Staphylococcus aureus |journal=J. Biol. Chem. |volume=242 |issue=5 |pages=1016–20 |year=1967 |pmid=6020427 |doi=}} *http://www.thermoscientificbio.com/dna-and-rna-modifying-enzymes/micrococcal-nuclease/2. ^{{cite journal |vauthors=Cusumano CL, Taniuchi H, Anfinsen CB |title=Staphylococcal nuclease (Foggi strain). I. Order of cyanogen bromide fragments and a "fourth" histidine residue |journal=J. Biol. Chem. |volume=243 |issue=18 |pages=4769–77 |year=1968 |pmid=5687719 |doi=}} 3. ^{{cite journal |vauthors=Arnone A, Bier J, etal |title=A High Resolution Structure of an Inhibitor Complex of the Extracellular Nuclease of Staphylococcus aureus: I. Experimental Procedures and Chain Tracing |journal=J. Biol. Chem. |volume=246 |pages=2303–2316 |year=1971 }}
External links
3 : Proteins|Molecular biology|EC 3.1.31 |
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