, selecting RNA ligands against various organic dyes. The Szostak lab also coined the term aptamer ... the cleavage activity of a ribozyme. Since the discovery of aptamers, many researchers have used aptamer ... k off math , math k on math constants and thermodynamic H, S parameters of aptamer target interaction .... It obtains aptamers in a few rounds of selection. Recent developments in aptamer based therapeutics have been rewarded in the form of the first aptamer based drug approved by the U.S. Food and Drug ..., a result of the aptamer s inherently low molecular weight. Unmodified aptamer applications currently ... diagnostic imaging. An example is a tenascin binding aptamer under development by Schering ... glycol PEG linkage, etc. both of which are used in Macugen, an FDA approved aptamer are available ... time scale. In addition to the development of aptamer based therapeutics, many researchers such as the Ellington ... lab has developed the Aptamer Database cataloging all published experiments. This is found ... greatly increases the binding affinity of the peptide aptamer to levels comparable to an antibody ... Cysteine s lateral chains being able to form a disulfide bridge. Peptide aptamer selection can be made ... Rapamycin or non immunosuppressive analogs. AptaBiD AptaBiD or Aptamer Facilitated Biomarker Discovery ... MV, Lechmann M, Musheev MU, Mak TW, Krylov SN title Aptamer facilitated biomarker discovery AptaBiD ... ja801951p ref AptaBiD is based on multi round generation of an aptamer or a pool of aptamers for differential ... cells ii aptamer based isolation of biomarkers from target cells and iii mass spectrometry identification ... title Pegaptanib, a targeted anti VEGF aptamer for ocular vascular disease journal Nat Rev Drug Discov ... Aptamer Base Category Nucleic acids Category Peptides Category Biotechnology Category Medical research de Aptamer fr Aptam re ja pl Aptamer fi Aptameeri tr Aptamer es Apt mero ar ... more details
Rfam box acc RF00522 description PreQ1 riboswitch abbreviation PreQ1 avg length 45.40 avg identity 69.00 type Cis reg riboswitch se Barrick JE ss Predicted Barrick JE release 10.0 The PreQ1 I riboswitch is a cis acting element identified in bacteria which regulates expression of genes involved in biosynthesis of the nucleoside queuosine from Guanosine triphosphate GTP ref name pmid17384645 cite journal author Roth A, Winkler WC, Regulski EE, Lee BW, Lim J, Jona I, Barrick JE, Ritwik A, Kim JN, Welz R, Iwata Reuyl D, Breaker RR title A riboswitch selective for the queuosine precursor preQ1 contains an unusually small aptamer domain journal Nat Struct Mol Biol volume 14 issue 4 pages 308 17 year 2007 pmid 17384645 doi 10.1038 nsmb1224 ref . This RNA element known as a riboswitch binds preQ sub 1 sub pre queuosine sub 1 sub , an intemediate in the queuosine pathway. Riboswitch function has been characterised in the bacterium Bacillus subtilis , where the riboswitch is located in the leader of the ykvJKLM queCDEF operon which encodes four genes necessary for queuosine production ref name pmid14660578 cite journal author Reader JS, Metzgar D, Schimmel P, de Cr cy Lagard V title Identification of four genes necessary for biosynthesis of the modified nucleoside queuosine journal J. Biol. Chem. volume 279 issue 8 pages 6280 5 year 2004 pmid 14660578 doi 10.1074 jbc.M310858200 ref . In this organism, PreQ sub 1 sub binding to the riboswitch aptamer is thought to induce premature Transcription genetics transcription termination within the leader to down regulate expression of these genes. The preQ sub 1 sub riboswitch is distinguished by its unusually small aptamer, compared to other riboswitches. Its atomic resolution three dimensional structure was determined. ref cite journal author Klein DJ, Edwards TE, Ferr D Amar AR title Cocrystal structure of a class I preQ1 riboswitch reveals a pseudoknot recognizing an essential hypermodified nucleobase journal Nat. Struct. Mol. B ... more details
. Solution structure of an ATP binding RNA aptamer reveals a novel fold. RNA 2 7 628 40. ref and adenosine ref name Huizenga Huizenga DE, Szostak JW. 1995 . A DNA aptamer that binds adenosine and ATP ... trial s are underway for a VEGF binding aptamer trade named Macugen in treating macular degeneration ... hybrid system References reflist External links http aptamer.freebase.com Aptamer Base Further reading ... more details
Smart ligands are affinity ligands selected with pre defined equilibrium math K d math , kinetic math k off math , math k on math and thermodynamic H, S parameters of biomolecular interaction. Ligands with desired parameters can be selected from large combinatorial libraries of biopolymers using instrumental separation techniques with well described kinetic behaviour, such as Kinetic capillary electrophoresis KCE , Surface Plasmon Resonance SPR , Microscale Thermophoresis MST ref name Baaske cite journal author Baaske P, Wienken CJ, Reineck P, Duhr S, Braun D title Optical Thermophoresis quantifies Buffer dependence of Aptamer Binding journal Angew. Chem. Int. Ed. volume 49 issue 12 pages 1 5 year 2010 month Feb pmid 20186894 pmc doi 10.1002 anie.200903998 url issn laysummary http www.physorg.com news186225693.html laysource Phsyorg.com ref ref name Wienken cite journal author Wienken CJ et al. title http www.nature.com ncomms journal v1 n7 full ncomms1093.html Protein binding assays in biological liquids using microscale thermophoresis. journal Nature Communications year 2010 month Oct volume 1 doi 10.1038 ncomms1093 ref and etc. Known examples of smart ligands include DNA smart aptamers however, RNA and peptide smart aptamer s can also be developed. Smart ligands can find a set of unique applications in biomedical research, drug discovery and proteomic studies. For example, a panel of DNA smart aptamers has been recently used to develop affinity analysis of proteins with ultra wide dynamic range of measured concentrations. References Reflist cite journal author Drabovich AP, Berezovski MV, Musheev MU, Krylov SN title Selection of smart small molecule ligands the proof of principle journal Anal. Chem. volume 81 issue 1 pages 490 4 year 2009 month January pmid 19055427 doi 10.1021 ac8023813 cite journal author Drabovich A, Berezovski M, Krylov SN title Selection of smart aptamers by equilibrium capillary electrophoresis of equilibrium mixtures ECEEM journal J. Am. ... more details
Unreferenced stub auto yes date December 2009 Drugbox IUPAC name image CAS number ATC prefix S01 ATC suffix LA03 PubChem 24847876 DrugBank C 294 H 342 F 13 N 107 Na 28 O 188 P 28 molecular weight 50 kilodaltons bioavailability protein bound metabolism elimination half life 10 days excretion pregnancy US B legal US Rx only routes of administration Intravitreal Pegaptanib sodium injection brand name Macugen is an anti angiogenics anti angiogenic medicine for the treatment of neovascular wet age related macular degeneration AMD . It was discovered by Gilead Sciences and licensed in 2000 to EyeTech Pharmaceuticals, now OSI Pharmaceuticals , for late stage development and marketing in the United States. Outside the U.S.A. Macugen is marketed by Pfizer . Approval was granted by the Food and Drug Administration United States U.S. Food and Drug Administration FDA in December 2004. Pegaptanib is a pegylated anti Vascular endothelial growth factor VEGF aptamer , a single strand of nucleic acid that binds with specificity to a particular target. Pegaptanib specifically binds to VEGF 165, a protein that plays a critical role in angiogenesis the formation of new blood vessels and increased permeability leakage from blood vessels , two of the primary pathological processes responsible for the vision loss associated with neovascular AMD. Pegaptanib is administered in a 0.3 mg dose once every six weeks by intravitreal injection. Ocular vascular disorder agents Category Ophthalmology Category Gilead Sciences Category Pfizer Pharma stub de Pegaptanib es Pegaptanib pl Pegaptanib ... more details
Rfam box acc SAM IV secondary structure description S adenosyl methionine SAM riboswitch, abbreviation SAM IV avg length 114.00 avg identity 67.00 type Cis reg riboswitch se Published 18369181 ss Published 18369181 release 9.1 SAM IV riboswitches are a kind of riboswitch that specifically binds S adenosylmethionine SAM ref cite journal author Weinberg Z, Regulski EE, Hammond MC, et al. title The aptamer core of SAM IV riboswitches mimics the ligand binding site of SAM I riboswitches journal RNA volume 14 issue 5 pages 822 year 2008 pmid 18369181 doi 10.1261 rna.988608 pmc 2327355 ref , a cofactor used in many methylation reactions. Originally identified by bioinformatics ref cite journal author Weinberg Z, Barrick JE, Yao Z, et al. title Identification of 22 candidate structured RNAs in bacteria using the CMfinder comparative genomics pipeline journal Nucleic Acids Res. volume 35 issue 14 pages 4809 19 year 2007 pmid 17621584 doi 10.1093 nar gkm487 pmc 1950547 ref , SAM IV riboswitches are largely confined to the Actinomycetales , an order of Bacteria . Conserved features of SAM IV riboswitch and experiments imply that they probably share a similar SAM binding site to another class of SAM binding riboswitches called SAM riboswitch SAM I riboswitches . However, the scaffolds of these two types of riboswitch appear to be quite distinct. See also SAM riboswitch S box leader SAM I riboswitch SAM II riboswitch SMK box riboswitch SAM III riboswitch SAM V riboswitch References references External links Rfam id RF00634 name SAM IV riboswitch DEFAULTSORT Sam Iv Riboswitch Category Cis regulatory RNA elements Category Riboswitch molecular cell biology stub ... more details
Riboswitches are cis acting regulatory elements located within the 5 untranslated region UTR of mRNA transcripts. These regulatory elements bind small molecules which results in a conformational change within the 5 UTR of the mRNA. The changes in the mRNA secondary structure subsequently result in changes in the expression of the adjacent open reading frame. Bioinformatic studies have identified several riboswitches present in M. florum . ref name pmid17911257 cite journal author Kim JN, Roth A, Breaker RR title Guanine riboswitch variants from Mesoplasma florum selectively recognize 2 deoxyguanosine journal Proc. Natl. Acad. Sci. U.S.A. volume 104 issue 41 pages 16092 7 year 2007 month October pmid 17911257 pmc 1999398 doi 10.1073 pnas.0705884104 url ref These riboswitches have been mapped to regions located upstream of the guaAB operon and resemble Purine riboswitch purine riboswitches . The riboswitches identified in M. florum can be classed as novel riboswitches as they deviate in sequence and structure within the loops regions that are required in aptamer binding compared to conventional purine riboswitches. Mutagenesis confirmed that changing nucleotides within the loop regions of this riboswitch altered the specificity for ligand binding. This study showed that the novel riboswitches have a greater diversity in ligands they bind as they were found to bind alternative ligands such as nucleosides . The novel riboswitches were all shown to lie upstream of a putative intrinsic terminator stem and this indicates that these riboswitches control Transcription genetics transcription termination. Comparative genomics has shown that these novel riboswitches are exclusive found in M. florum and not present in other strains of bacteria. References reflist Category Riboswitch ... more details
Infobox rfam Name SAM V image SAM V SScon.png width caption Conserved secondary structure of the SAM V riboswitch. Symbol SAM V AltSymbols Rfam RNA type Cis regulatory element Cis reg Riboswitch Tax domain Metagenomics Marine metagenome SAM V riboswitch is the fifth known riboswitch to bind S adenosyl methionine SAM . It was first discovered in the marine organism Pelagibacter ubique Candidatus Pelagibacter ubique and can also be found in marine metagenomics metagenomes . ref name Mey09 cite journal author Meyer MM, Ames TD, Smith DP, et al. title Identification of candidate structured RNAs in the marine organism Candidatus Pelagibacter ubique journal BMC Genomics volume 10 issue pages 268 year 2009 pmid 19531245 pmc 2704228 doi 10.1186 1471 2164 10 268 url http www.biomedcentral.com 1471 2164 10 268 accessdate 2010 08 20 ref SAM V features a similar consensus sequence and secondary structure as the binding site of SAM II riboswitch , but bioinformatics scans cluster the two aptamer aptamers independently. These similar binding pockets suggest that the two riboswitches have undergone convergent evolution . ref name Poi09 cite journal author Poiata E, Meyer MM, Ames TD, Breaker RR title A variant riboswitch aptamer class for S adenosylmethionine common in marine bacteria journal RNA volume 15 issue 11 pages 2046 56 year 2009 month November pmid 19776155 pmc 2764483 doi 10.1261 rna.1824209 url http rnajournal.cshlp.org cgi pmidlookup?view long&pmid 19776155 accessdate 2010 08 20 ref SAM binding was confirmed using equilibrium dialysis . The riboswitch has been characterised as a tandem riboswitch it is able to regulate both translation genetics translation and transcription genetics transcription . When SAM is present in high concentration, SAM II will bind its ligand and form a terminator genetics terminator stem to halt transcription. If SAM exists in lower concentrations, SAM V will be transcribed and, if SAM concentration should then increase, it can bind SAM and ... more details
Rfam box acc RF00504 description Glycine riboswitch abbreviation Glycine avg length 85.60 avg identity 63.00 type Cis reg riboswitch se Barrick JE, Breaker RR ss Predicted Barrick JE, Breaker RR release 10.0 The bacterial glycine riboswitch is an Cis regulatory element RNA element that can bind the amino acid glycine . Glycine riboswitch es usually consist of two metabolite binding aptamers domains with similar structures in tandem. The aptamers cooperatively bind glycine to regulate the expression of downstream genes. In Bacillus subtilis , this riboswitch is found upstream of the gcvT operon which controls glycine degradation. It is thought that when glycine is in excess it will bind to both aptamers to activate these genes and facilitate glycine degradation. ref name breaker cite journal last Mandal first M coauthors Lee M, Barrick JE, Weinberg Z, Emilsson GM, Ruzzo WL, Breaker RR year 2004 title A glycine dependent riboswitch that uses cooperative binding to control gene expression journal Science volume 306 pages 275&ndash 279 pmid 15472076 doi 10.1126 science.1100829 issue 5694 ref Examples of the glycine riboswitch exhibit sigmoidal binding curves with Hill coefficient s greater than one, indicating cooperativity positive cooperativity between the two aptamer domains. ref name breaker ref cite journal last Kwon first M coauthors Strobel SA year 2008 title Chemical basis of glycine riboswitch cooperativity journal RNA volume 14 pages 25&ndash 34 pmid 18042658 doi 10.1261 rna.771608 issue 1 pmc 2151043 ref This type of binding is unusual for a riboswitch and is thought to have important physiological consequences. Glycine levels in a bacterial cell must be maintained at a certain baseline level to support protein synthesis . Positive cooperativity would allow genes for glycine degradation to be turned on more efficiently at glycine levels above this baseline concentration, which could confer a growth advantage under certain nutrient conditions. References refer ... more details
Rfam box acc RF00521 description SAM riboswitch alpha proteobacteria abbreviation SAM alpha avg length 78.20 avg identity 68.00 type Cis reg riboswitch se Barrick JE ss Predicted Barrick JE release 10.0 The SAM II riboswitch is a Cis regulatory element RNA element found predominantly in alpha proteobacteria that binds S adenosyl methionine SAM ref name pmid16086852 cite journal author Corbino KA, Barrick JE, Lim J, et al. title Evidence for a second class of S adenosylmethionine riboswitches and other regulatory RNA motifs in alpha proteobacteria journal Genome Biol. volume 6 issue 8 pages R70 year 2005 pmid 16086852 doi 10.1186 gb 2005 6 8 r70 pmc 1273637 ref . Its structure and sequence appear to be unrelated to the SAM riboswitch S box leader SAM riboswitch found in Gram positive bacteria . This SAM riboswitch is located upstream of the metA and metC genes in Agrobacterium tumefaciens , and other methionine and SAM biosynthesis genes in other alpha proteobacteria. Like the other SAM riboswitch, it probably functions to turn off expression of these genes in response to elevated SAM levels. A significant variant of SAM II riboswitches was found in Pelagibacter ubique and related marine ocean marine bacteria and called SAM V riboswitch SAM V . ref cite journal author Poiata E, Meyer MM, Ames TD, Breaker RR title A variant riboswitch aptamer class for S adenosylmethionine common in marine bacteria journal RNA volume 15 issue 11 pages 2046 56 year 2009 month November pmid 19776155 pmc 2764483 doi 10.1261 rna.1824209 url ref Also, like many structured RNAs, SAM II riboswitches can tolerate long loops between their stems. ref name Weinberg2010 cite journal author Weinberg Z, Wang JX, Bogue J, et al. title Comparative genomics reveals 104 candidate structured RNAs from bacteria, archaea and their metagenomes journal Genome Biol volume 11 issue 3 pages R31 year 2010 month March pmid 20230605 doi 10.1186 gb 2010 11 3 r31 url pmc 2864571 ref Structure The SAM II riboswitch ... more details
File PreQ1 II.svg left frame Consensus secondary structure of PreQ sub 1 sub II riboswitches. Layout is similar to that used in previously published depictions. ref name Weinberg2007 ref name meyer Rfam box acc preQ1 II secondary structure description preQ1 II pre queuosine riboswitch abbreviation preQ1 II avg length 107.90 avg identity 75.00 type Cis reg riboswitch se Published PMID 18305186 Weinberg Z, Meyer MM, Gardner PP ss Published PMID 18305186 Gardner PP release 9.1 PreQ1 II riboswitches form a class of riboswitch es that specifically bind pre queosine sub 1 sub PreQ sub 1 sub , a precursor of the modified nucleoside queuosine ref name meyer cite journal author Meyer MM, Roth A, Chervin SM, Garcia GA, Breaker RR title Confirmation of a second natural preQ1 aptamer class in Streptococcaceae bacteria journal RNA volume 14 issue 4 pages 685 year 2008 pmid 18305186 doi 10.1261 rna.937308 pmc 2271366 ref . They are found in certain species of Streptococcus and Lactococcus , and were originally identified as a conserved RNA secondary structure called the COG4708 motif ref name Weinberg2007 cite journal author Weinberg Z, Barrick JE, Yao Z, et al. title Identification of 22 candidate structured RNAs in bacteria using the CMfinder comparative genomics pipeline journal Nucleic Acids Res. volume 35 issue 14 pages 4809 19 year 2007 pmid 17621584 doi 10.1093 nar gkm487 pmc 1950547 ref . All known members of this riboswitch class appear to control members of COG4708 genes. These genes are predicted to encode membrane bound proteins and have been proposed to be a transporter of preQ sub 1 sub , or a related metabolite, based on their association with preQ sub 1 sub binding riboswitches ref name meyer . PreQ1 II riboswitches have no apparent similarities in sequence or structure to preQ1 riboswitch preQ1 I riboswitches , a previously discovered class of preQ sub 1 sub binding riboswitches. PreQ sub 1 sub thus joins S adenosylmethionine as the second metabolite to be found ... more details
Rfam box acc RF00380 description ykoK leader abbreviation ykoK avg length 168.00 avg identity 64.00 type Cis reg se Barrick JE, Breaker RR ss Predicted Barrick JE, Breaker RR release 10.0 Image PDB 2qbz EBI.png thumb 200px left A 3D representation of the Ykok leader. Structure of the M box riboswitch aptamer domain from Bacillus subtilis . ref name pmid17803910 cite journal author Dann CE, Wakeman CA, Sieling CL, Baker SC, Irnov I, Winkler WC title Structure and mechanism of a metal sensing regulatory RNA. journal Cell volume 130 issue 5 pages 878 92 year 2007 pmid 17803910 doi 10.1016 j.cell.2007.06.051 ref The Ykok leader or M box is a Mg sup 2 sup sensing Cis regulatory element RNA structure that controls the Gene expression expression of Magnesium transporter Magnesium ion transport proteins in bacteria. The Ykok leader was originally described as a conserved sequence conserved sequence with potential riboswitch function found upstream molecular biology upstream of the B. subtilis ykoK gene and genes with related functions in other bacteria. ref name Barrick cite journal last Barrick first JE coauthors Corbino KA, Winkler WC, Nahvi A, Mandal M, Collins J, Lee M, Roth A, Sudarsan N, Jona I, Wickiser JK, Breaker RR year 2004 title New RNA motifs suggest an expanded scope for riboswitches in bacterial genetic control journal Proc Natl Acad Sci USA volume 101 pages 6421&ndash 6426 pmid 15096624 doi 10.1073 pnas.0308014101 issue 17 pmc 404060 ref Examples of the conserved M box RNA structure occur upstream of each of the three major families of Mg sup 2 sup transporters in various bacterial species. ref name pmid17803910 ref The molecular structure of the M box example upstream of the B. subtilis ykoK gene includes six bound Mg sup 2 sup ions. Biochemical studies indicate that this M Box RNA compacts in the presence of Mg sup 2 sup and other divalent ions. This folding process appears to disrupt an antiterminator structure, and thereby allow a Rho independent transcr ... more details
to have potential in facilitating drug discovery by allowing the detection of aptamer binding by comparison ... of Aptamer Binding journal Angewandte Chemie International Edition volume 49 issue 12 pages ... more details
aptamer folding by interacting with P2 kink turn motif. ref cite journal last Heppell first B coauthors Lafontaine DA year 2008 title Folding of the SAM aptamer is determined by the formation of a K ... more details
Image Figure 2d.200.jpg The L1 Ligase Ribozyme 2.6 crystal structure right thumb 200px The RNA Ligase ribozyme was the first of several types of Ribozyme Synthetic ribozymes synthetic ribozymes produced by in vitro evolution and selection techniques. They are an important class of ribozymes because they catalyze the assembly of RNA fragments into phosphodiester RNA polymers, a reaction required of all extant nucleic acid polymerases and thought to be required for any self replicating molecule. Ideas that the origin of life may have involved the first self replicating molecules being ribozymes are called RNA World RNA World hypotheses . Ligase ribozymes may have been part of such a pre biotic RNA world. In order to copy RNA, fragments or monomers individual building blocks that have Nucleotide 5 triphosphates must be ligated together. This is true for modern protein based Rna Polymerase polymerases , and is also the most likely mechanism by which a ribozyme self replicase in an RNA world might function. Yet no one has found a natural ribozyme that can perform this reaction. In vitro evolution and selection RNA Directed evolution in vitro evolution or Systematic Evolution of Ligands by Exponential Enrichment SELEX enables the artificial evolution and selection of RNA molecules that possess a desired property, such as binding affinity for a particular ligand or an activity such as that of an enzyme or catalyst . The first such selections involved isolation of various aptamer s that bind to small molecules. The first catalytic RNAs produced by in vitro evolution were RNA ligases , catalytic RNAs that join two RNA fragments to produce a single adduct . Systematic Evolution of Ligands by Exponential Enrichment RNA test tube in vitro evolution and selection has thus enabled several research groups to discover RNA sequences that can in fact catalyze the required chemical reaction for 5 triphosphate RNA fragment ligation, and one group has even produced a functional RNA po ... more details
called aptamer s. ref cite journal author Nou X, Kadner RJ title Adenosylcobalamin inhibits ribosome ... conceptually divided into two parts an aptamer and an expression platform. The aptamer directly ... in the aptamer. The expression platform is what regulates gene expression. Expression platforms ... cooperative binding , which is accomplished by two adjacent aptamer domains in the same mRNA ... believed was the domain of protein s or artificially constructed RNAs called aptamer s. The existence ... more details
has been used to describe a blot of proteins on PVDF membrane where the probe is an aptamer rather ... the interaction is between a DNA molecule the aptamer and a protein, rather than two DNA molecules ... more details
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