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INTEGRATEDDNATECHNOLOGIESPRODUCTSMODIFICATIONSModified Bases2’-O-Methyl RNA BasesmA MW: 343.2 mG MW: 359.2mC MW: 319.2 mU MW: 320.22’-O-Methyl RNA is a naturally occurring modification of RNA found in tRNA and other small RNAs that arises as a posttranscriptionalmodification. Oligonucleotides can be directly synthesized that contain 2’-O-Methyl RNA. This modificationincreases Tm of RNA:RNA duplexes but results in only small changes in RNA:DNA stability. It is stabile with respect to attackby single-stranded ribonucleases and is typically 5- to 10-fold less susceptible to DNases than DNA. It is commonly usedin antisense oligos as a means to increase stability and binding affinity to the target message. 2’-O-Methyl RNA bases areindicated using lower case m (mU for example) in the IDT ordering system.'5BaseOOOOCH 3O P O -3’-Ribo PrimersO3'Ribo A MW: 329.2 Ribo C MW: 305.2Ribo G MW: 345.2 Ribo U MW: 306.2PCR primers containing a 3’-terminal ribose can be used to prevent cross-contamination of amplified sequences. 15’ INT. 3’— — a'5NNH2NNNRibo AOOReference:OHOH1. Use of PCR primers containing a 3’-terminal ribose residue to prevent cross-contamination of amplified sequences. Walder, R.Y. and Walder, J.A. NucleicAcids Research, 21:4339-43 (1993).Iso-dC and Iso-dGIso-dG and Iso-dC are novel DNA bases licensed from EraGen Biosciences, Inc (www.eragen.com). Iso-dC and Iso-dG arechemical variants of cytosine and guanine, respectively. Iso-dC will hydrogen bond with Iso-dG but not with dG. Similarly,Iso-dG will base pair with Iso-dC but not with dC. 1 Incorporation of these novel bases into DNA effectively expands the geneticalphabet and permits synthesis of oligonucleotides that have increased specificity and decreased mismatch hybridizationpotential. For example, an oligo containing Iso-dC can be designed so that it will hybridize to a complementary oligocontaining Iso-dG, but will not hybridize to any naturally occurring nucleic acid sequence. Iso-dG and Iso-dC triphosphates,which can be incorporated opposite Iso-dG and Iso-dC using traditional polymerases, are available from EraGen.Oligonucleotides that contain either or both iso-bases require IE-HPLC purification.HNNIso-dC MW: 303.25’ INT. 3’a a —IE-HPLC requiredReference:ONHN5-Me-Iso-dCNHNHNHON1. Enzymatic recognition of the base pair between isocytidine and isoguanosine. Switzer, C.Y., Moroney, S.E., and Benner, S.A. Biochemistry, 32:10489-96(1993).NIso-dG©2008 Integrated DNA Technologies www.idtdna.com79HNNHN5-Me-dCOHONHNNHNdG