Ribonuclease T1

{{Short description|Class of enzymes}} {{Distinguish|ribonuclease T|ribonuclease T2}} {{DISPLAYTITLE:Ribonuclease T₁}} {{infobox enzyme | Name = Ribonuclease T₁ | EC_number = 4.6.1.24 | CAS_number = 9026-12-4 | GO_code = 0046589 | image = 9rnt.jpg | width = 270 | caption = }} {{Infobox protein | Name = Ribonuclease T₁ | caption = Ribonuclease T₁ from ''Aspergillus oryzae''.<ref name="pmid9047372">{{PDB|1ygw}}; {{cite journal |vauthors=Pfeiffer S, Karimi-Nejad Y, Rüterjans H | year = 1997 | title = Limits of NMR structure determination using variable target function calculations: ribonuclease T₁, a case study | journal = Journal of Molecular Biology | volume = 266 | issue = 2 | pages = 400–423 | doi = 10.1006/jmbi.1996.0784 | pmid = 9047372 }}</ref> | image = RNase-T1_pdb_1ygw.jpg | HGNCid = | Symbol = rntA | AltSymbols = | EntrezGene = | OMIM = | RefSeq = | UniProt = P00651 | PDB = 1YGW | ECnumber = 4.6.1.24 | Chromosome = | Arm = | Band = | LocusSupplementaryData = }}

'''Ribonuclease T₁''' ({{EC number|4.6.1.24}}, ''guanyloribonuclease'', ''Aspergillus oryzae ribonuclease'', ''RNase N1'', ''RNase N2'', ''ribonuclease N3'', ''ribonuclease U1'', ''ribonuclease F1'', ''ribonuclease Ch'', ''ribonuclease PP1'', ''ribonuclease SA'', ''RNase F1'', ''ribonuclease C2'', ''binase'', ''RNase Sa'', ''guanyl-specific RNase'', ''RNase G'', ''RNase T₁'', ''ribonuclease guaninenucleotido-2'-transferase (cyclizing)'', ''ribonuclease N3'', ''ribonuclease N1'') is a fungal endonuclease that cleaves single-stranded RNA after guanine residues, i.e., on their 3' end; the most commonly studied form of this enzyme is the version found in the mold ''Aspergillus oryzae''. Owing to its specificity for guanine, RNase T₁ is often used to digest denatured RNA prior to sequencing. Similar to other ribonucleases such as barnase and RNase A, ribonuclease T₁ has been popular for folding studies.<ref> {{cite journal |vauthors=Pace CN, Heinemann U, Hahn U, Saenger W | year = 1991 | title = Ribonuclease T₁: Structure, Function, and Stability | journal = Angewandte Chemie | volume = 30 | issue = 4 | pages = 343–360 | doi = 10.1002/anie.199103433 }}</ref>

Structurally, ribonuclease T₁ is a small α+β protein (104 amino acids) with a four-stranded, antiparallel beta sheet covering a long alpha helix (almost five turns). RNase T₁ has two disulfide bonds, Cys2-Cys10 and Cys6-Cys103, of which the latter contributes more to its folding stability;<ref> {{cite journal |vauthors=Pace CN, Grimsley GR, Thomson JA, Barnett BJ | year = 1988 | title = Conformational stability and activity of ribonuclease T₁ with zero, one, and two intact disulfide bonds | journal = Journal of Biological Chemistry | volume = 263 | issue = 24 | pages = 11820–11825 | doi = 10.1016/S0021-9258(18)37859-1 | pmid=2457027 | doi-access = free }}</ref> complete reduction of both disulfides usually unfolds the protein, although its folding can be rescued with high salt concentrations.<ref> {{cite journal |vauthors=Oobatake M, Takahashi S, Ooi T | year = 1979 | title = Conformational stability of ribonuclease T₁. II. Salt-induced renaturation | journal = Journal of Biochemistry | volume = 86 | issue = 1 | pages = 65–70 | pmid = 113396 }}</ref>

RNase T₁ also has four prolines, two of which (Pro39 and Pro55) have ''cis'' isomers of their X-Pro peptide bonds. Nonnative isomers of these prolines can retard conformational folding dramatically,<ref> {{cite journal |vauthors=Mayr LM, Odefey CO, Schutkowski M, Schmid FX | year = 1996 | title = Kinetic analysis of the unfolding and refolding of ribonuclease T₁ by a stopped-flow double-mixing technique | journal = Biochemistry | volume = 35 | issue = 17 | pages = 5550–5561 | doi = 10.1021/bi953035y | pmid = 8611546 }}</ref> folding on a characteristic time scale of 7,000 seconds (almost two hours) at 10&nbsp;°C and pH 5.<ref> {{cite journal |vauthors=Mullins LS, Pace CN, Raushel FM | year = 1997 | title = Conformational stability of ribonuclease T₁ measured by hydrogen-deuterium exchange | journal = Protein Science | volume = 6 | issue = 7 | pages = 1387–1395 | doi = 10.1002/pro.5560060702 | pmc = 2143755 | pmid = 9232639 }}</ref>

==References== {{Reflist}}

==External links== * {{MeshName|Ribonuclease+T1}}

{{Esterases}}

Category:Ribonucleases

{{enzyme-stub}}