Base Modifications

RNA Base Analogs

A practical catalogue of RNA base analogs and related base-level chemistries—covering universal/wobble bases, epitranscriptomic mimics, convertible/reactive bases, artificial base pairs, hapten-tagged functional bases, intercalators, and fluorescent bases—so you can tune stability, translation, and assay readouts.

ISO 9001:2015 ISO 13485:2016 GLP/GMP-aligned

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Applications of RNA Base Analogs

RNA Base Analogs expand the chemical and functional space of natural ribonucleotides. By altering hydrogen bonding, stacking, or electronic properties, these analogs enable applications in epitranscriptomic research (m6A, m5C, pseudouridine), structural probing (thio- and halogenated bases), fluorescent reporting (2-aminopurine, pyrrolo-C, ribo-tC°), and therapeutic engineering (stability-enhancing 2′-F, 2′-OMe, MOE variants). They are powerful tools for dissecting RNA–protein interactions, mapping modifications, designing diagnostic probes, and developing next-generation RNA medicines.

mRNA Therapeutics  m1Ψ and m6A are cornerstone modifications in vaccine and therapeutic RNA design.
Research, diagnostics, and therapeutics

Design Considerations

  • Stability & Tm: 2,6‑diaminopurine, 2′‑F, and intercalator bases generally raise duplex Tm, while universal bases lower it.
  • Enzyme compatibility: Bulky analogs may inhibit transcription or reverse transcription—validate with your chosen polymerase.
  • Fluorescence: tC°, pyrrolo‑C, and 2‑AP are minimally perturbing, environment‑sensitive probes.
  • Placement: Use stabilizers sparingly and distribute bulky groups to avoid helix distortion.
  • Therapeutics: Synthetic epitranscriptomic marks (m6A, m1Ψ) are central to mRNA vaccine efficacy.

RNA Base Analogs

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RNA Base Analogs expand the chemical and functional space of natural ribonucleotides. By altering hydrogen bonding, stacking, or electronic properties, these analogs enable applications in epitranscriptomic research (m6A, m5C, pseudouridine), structural probing (thio- and halogenated bases), fluorescent reporting (2-aminopurine, pyrrolo-C, ribo-tC°), and therapeutic engineering (stability-enhancing 2′-F, 2′-OMe, MOE variants). They are powerful tools for dissecting RNA–protein interactions, mapping modifications, designing diagnostic probes, and developing next-generation RNA medicines.

Hide Products & Notes
Products Description Typical Use Notes Code
1‑Methyl A (RNA) N1‑methyladenosine Translation/structure mapping; epitranscriptomics Watson–Crick edge blocked; protonated at phys. pH; synonym of m1A [m1A]
1‑Methyl‑PseudoUridine N1‑methyl‑pseudouridine mRNA therapeutics; immunogenicity reduction Enhances translation; synonym of m1‑ψ [m1ψ]
2,6‑Diaminopurine (2‑amino‑A) A analog with extra exocyclic amine Increase A:U pairing strength Tends to raise Tm ~1–2 °C/base [DAP]
2′‑O‑Methyl‑C Phosphodithioate 2′‑OMe‑C with PS2 backbone Nuclease resistance; affinity tuning RNase‑H incompatible (2′‑OMe) [2OMeC-PS2]
2′‑O‑Methyl‑G Phosphodithioate 2′‑OMe‑G with PS2 backbone Stability in probes/ASO designs Increased hydrophobicity vs PO [2OMeG-PS2]
2′‑O‑Methyl‑U Phosphodithioate 2′‑OMe‑U with PS2 backbone Nuclease resistance; duplex tuning Use for challenging matrices [2OMeU-PS2]
2‑Amino Purine ribose Fluorescent A analog (RNA) Stacking/conformation reporter Quenched in duplex; environment‑sensitive [2‑A‑rP]
2‑Aminopurine Fluorescent A analog Folding/kinetics assays Use RNA or DNA version as needed [2AP]
2′‑F Inosine 2′‑fluoro‑inosine Wobble pairing with added stability Pairs with A/C/G/U (bias I–C) [fI]
2′‑Fluoro Bases 2′‑F A/C/G/U set Stability, nuclease resistance General 2′‑F family [fN]
2′‑Fluoro deoxyadenosine 2′‑F‑A (DNA) Hybrid stability studies DNA context [fA]
2′‑Fluoro deoxycytidine 2′‑F‑C (DNA) Affinity/structure probes DNA context [fC]
2′‑Fluoro deoxyguanosine 2′‑F‑G (DNA) Stability tuning DNA context [fG]
2′‑Fluoro deoxyuridine 2′‑F‑U (DNA) Photochem./NMR probes DNA context [fU]
FANA‑N 2′‑fluoro‑arabino nucleoside XNA research; nuclease resistance Requires FANA pairing rules [FANA‑N]
2′‑O‑Me‑5‑Me‑C 5‑methyl‑C on 2′‑OMe sugar Affinity boost; epitranscriptomic mimic Raises Tm [m5mC]
2′‑O‑Methyl‑5‑Fluoro‑U 5‑F‑U on 2′‑OMe sugar NMR/structural probes Small halogen; mild Tm effect [2OMe-5F-U]
2′‑O‑Methyl adenosine mA Stability; nuclease resistance RNase‑H incompatible [mA]
2′‑O‑Methyl bases Set of 2′‑OMe A/C/G/U ASO wings; probe stabilization General entry [mN]
2′‑O‑Methyl cytidine mC Affinity/stability Common in probes [mC]
2′‑O‑Methyl guanosine mG Stability; folding control Use sparingly near G‑runs [mG]
2′‑O‑Methyl inosine mI Stabilized wobble Pairs broadly; bias I–C [mI]
2′‑O‑Methyl uridine mU Stability; nuclease resistance Common in ASO wings [mU]
2′‑O‑Methyl‑2,6‑Diaminopurine DAP on 2′‑OMe Strong A:U pairing High Tm; use sparingly [2OMe-DAP]
2′‑O‑Methyl‑5‑Bromo‑U 5‑Br‑U on 2′‑OMe Photo‑crosslinking; structure UV‑sensitive [2OMe-5Br-U]
2′‑O‑Methyl‑5‑Me‑U m5U on 2′‑OMe sugar Epigenetic studies; duplex stability; reader protein assays Raises Tm modestly [2OMe-5Me-U]
2′‑O‑Methyl‑5‑Me‑C m5U on 2′‑OMe sugar Epigenetic studies; duplex stability; reader protein assays Raises Tm modestly [2OMe-5Me-C]
2′‑O‑Methyl‑A Phosphodithioate mA with PS2 linkage Nuclease resistance Backbone sulfur x2 [2OMeA-PS2]
2′‑MOE‑5‑Me‑C 5‑mC on 2′‑O‑methoxyethyl sugar ASO/siRNA‑like stabilization High affinity; nuclease resistance [MOE‑mC]
2′‑MOE‑5‑Me‑U 5‑mU on 2′‑MOE Affinity/stability Use for probe robustness [MOE‑mU]
2′‑MOE‑A A on 2′‑MOE ASO wings; nuclease resistance RNase‑H incompatible [MOE‑A]
2′‑MOE Bases 2′‑MOE A/C/G/U set Stability & PK improvements General entry [MOE‑N]
2′‑MOE‑G G on 2′‑MOE Stabilize G‑poor regions Combine with PS backbones [MOE‑G]
2‑Thio‑U (s2U) S at C2 of uracil tRNA decoding; crosslinking Red‑shifted absorbance [s2U]
3′‑O‑methyl bases (2′–5′ linked) 3′‑O‑Me N with 2′–5′ linkage Block extension; structure probes Non‑extendable; mapping tools [3OmN]
3′‑O‑methyl rA (2′–5′) 3′‑O‑Me‑A, 2′–5′ RNase footprinting; blocking Terminates polymerases [3OmA]
3′‑O‑methyl rC (2′–5′) 3′‑O‑Me‑C, 2′–5′ As above Use internally or at ends [3OmC]
3′‑O‑methyl rG (2′–5′) 3′‑O‑Me‑G, 2′–5′ As above [3OmG]
3′‑O‑methyl rI (2′–5′) 3′‑O‑Me‑I, 2′–5′ Wobble with block [3OmI]
3′‑O‑methyl rU (2′–5′) 3′‑O‑Me‑U, 2′–5′ Extension block [3OmU]
3′‑rA (2′–5′) 2′–5′‑linked rA Structure mapping; ligation studies Non‑canonical linkage [3rA2‑5]
3′‑rC (2′–5′) 2′–5′‑linked rC As above [3rC2‑5]
3′‑rG (2′–5′) 2′–5′‑linked rG As above [3rG2‑5]
3′‑rU (2′–5′) 2′–5′‑linked rU As above [3rU2‑5]
4‑Thio‑U (s4U) S at C4 of uracil Photo‑crosslinking (PAR‑CLIP) UV‑A reactive [s4U]
5‑Bromo‑rC Br at C5 of rC Photo‑crosslinking; phasing Heavy atom derivative [5‑Br‑rC]
5‑Bromo‑rU Br at C5 of rU Photo‑crosslinking; RNA structure UV‑sensitive [5‑Br‑rU]
5‑Iodo‑rC I at C5 of rC Crystallography; crosslinking Strong X‑ray scatterer [5‑I‑rC]
5‑Iodo‑rU I at C5 of rU Photocrosslinking; phasing Heavy halogen [5‑I‑rU]
5‑Methyl‑Cytosine m5C (RNA) Epitranscriptomics; reader assays Alters protein recognition [5mrC]
5‑Methyl‑U m5U Affinity tuning; structural studies Mild Tm increase [m5U]
6‑Thio‑rG S at C6 of G Crosslinking; metal coordination Photosensitizer; reactive sulfur [S6‑rG]
8‑Aza‑7‑deaza‑A Ring‑modified A Electronics/stacking tuning Specialty structural analog [8A-7dA]
8‑Azanebularine (ribo) Transition‑state/lesion mimic Deaminase/repair studies Potent enzyme probe [8‑AzaN]
8‑Bromo‑rG Br at C8 of rG Structure/crystallography; photo‑chem Bulky at C8; conformational bias [8‑Br‑rG]
8‑Oxo‑rG Oxidized lesion analog Oxidative damage/repair studies Mispairs with A [8‑Oxo‑rG]
5′‑Adenylation (rApp) Pre‑adenylated RNA 5′ Adapter ligation without ATP For Rnl2‑based ligations [5rApp]
Amino C6‑U Primary amine on U via C6 linker NHS‑ester labeling; conjugation Post‑synthetic coupling [AmC6U]
Aminoallyl rU Allylic amine on U Dye/hapten labeling Good for fluorescent tags [AmAll‑rU]
Dihydrouracil (ribo) Reduced 5,6‑double bond tRNA flexibility/structure Destabilizes stacking; Tm↓ [5‑6‑DHrU]
Inosine (ribo) Wobble base (rI) Degenerate sites; tRNA mimicry Pairs A/C/G/U with bias [rI]
Inverted rA Reverse (3′–3′ or 5′–5′) linkage Nuclease blocking; end capping Terminates extension [Inv‑rA]
Inverted rC Reverse linkage As above [Inv‑rC]
Inverted rG Reverse linkage As above [Inv‑rG]
Inverted rU Reverse linkage As above [Inv‑rU]
L‑RNA rA Mirror‑image rA (L‑form) Spiegelmer/aptamer work; nuclease resistance Orthogonal to natural enzymes [L‑rA]
L‑RNA rC L‑rC As above [L‑rC]
L‑RNA rG L‑rG As above [L‑rG]
L‑RNA rU L‑rU As above [L‑rU]
N1‑Methyl‑PseudoUridine m1‑ψ‑rU mRNA therapy optimization Reduces innate immune sensing [m1‑psi‑rU]
N1‑Methyl rA (m1A) m1A Translation/structure mapping Watson–Crick edge blocked [m1A]
N3‑Methyl‑C N3‑alkylated cytidine Alkylation/repair studies Positively charged; pairing disrupted [m3C]
N3‑Methyl‑rU N3‑methyl‑uridine Lesion/repair studies Disrupts U:A pairing [m3U]
N4‑Ethyl‑rC N4‑ethyl cytidine Protein recognition studies Alters H‑bond donor pattern [N4‑Et‑rC]
N6‑Benzyl‑A N6‑benzyl adenosine Reader/ligand screening Bulky N6; pairing perturbed [bn6A]
N6‑dimethyl rA m6,6A Translation/structure effects Positively charged tendency [m6‑6A]
N6‑isopentenyl‑rA (i6A) Isopentenyl A (tRNA‑like) tRNA modification studies Hydrophobic isoprenoid at N6 [N6‑i6A]
N6‑Methyl rA (m6A) m6A Epitranscriptomics Reader/writer/eraser assays [m6A]
Pseudouridine (ribo) Ψ (C‑glycosidic isomer) Stability/translation enhancement Improves folding; lowers innate sensing [psi‑rU]
Pyrrolo‑C Fluorescent C analog RNA folding/hybridization reporter Excitation ~350 nm; environment‑sensitive [Pyrrolo-C]
rAbasic Site (abasic furan) Stable AP site (RNA) Block extension; lesion mimic Behaves like a gap [rABS]
riboadenosine rA (natural) Controls; standards Reference ribonucleoside [rA]
ribocytidine rC (natural) Controls; standards [rC]
riboguanosine rG (natural) Controls; standards [rG]
ribouridine rU (natural) Controls; standards [rU]
Thymidine Ribo rT (ribothymidine) tRNA motif studies Natural in tRNA T‑loop [rT]
Zebularine (RNA) C analog lacking 4‑amino Deaminase/DNMT studies Epigenetic tool; lesion mimic [rZ]
Technical Notes
Applications of RNA Base Analogs
Custom RNA, chimeric constructs, and nuclease-resistant analogs

Bio-Synthesis offers advanced synthesis of RNA oligonucleotides with a wide range of chemical modifications, including fluorescent probes with quenchers, DNA/RNA chimeric constructs, and combinations of 2′-O-methyl bases, 2′-fluoro bases, and phosphorothioate linkages.

Using state-of-the-art synthesizers and proprietary long-coupling protocols based on β-cyanoethyl phosphoramidite chemistry, Gene Link produces ultra-clean oligos with high fidelity. Because native RNA is highly susceptible to nuclease degradation, incorporation of 2′-O-methyl or 2′-fluoro bases provides enhanced resistance while maintaining RNA-like hydrogen bonding. 2′-O-methyl phosphoramidites also couple more efficiently than standard RNA monomers, yielding longer, more stable oligos.

Bio-Synthesis also customizes DNA/RNA chimeric oligos with user-defined ribo, deoxy, or 2′-O-methyl residues, and can substitute standard phosphodiester bonds with phosphorothioate linkages. Full or partial substitution delivers greater nuclease resistance—particularly valuable for antisense studies.

2′-Fluoro nucleosides adopt an RNA-like C3′-endo conformation, supporting the A-form helix upon hybridization. These modifications raise duplex stability and are applied in diverse settings:

  • Antisense oligos: 2′-F residues increase Tm and retain RNase H activity; phosphorothioation further improves resistance.
  • Aptamers: Incorporation of 2′-F pyrimidines enhances both nuclease stability and binding affinity.
  • siRNA: 2′-F substitutions boost plasma stability and, when combined with 2′-O-methyl bases, greatly improve potency in gene silencing.
  • LNA alternatives: 2′-F residues provide similar thermal stability and nuclease resistance at lower cost.
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Universal, Wobble & Degenerate Bases

Tolerate variation or enpill diversity

Degenerate bases allow multiple nucleotides at a position; in RNA, inosine (rI) is the classic wobble base. IUB pills (R,Y,M,K,S,W,H,B,D,V,N) define mixtures used for libraries or variant coverage. Programmed delivery sets base ratios (e.g., N = A+C+G+U).

Show Products & Notes
Product Description Typical Use Notes Code
Inosine (rI) Universal wobble base in RNA tRNA wobble; degenerate primer/probe sites Pairs with A/C/G/U with bias rI
2′‑O‑methyl Inosine Inosine with 2′‑OMe ribose Stabilized wobble positions Improved nuclease resistance mI
5‑nitroindole (ribo) Non‑H‑bonding universal analog Bypass variable sites in RNA constructs Tm↓; avoid adjacent placements 5NI‑r
Degenerate Base (Mixed Base) Mixture of A/C/G/U at one position Library synthesis; polymorphism coverage IUB pills define ratio Mix

Note: ESI‑MS is not performed on mixed‑base oligos due to sequence ambiguity.


Technical Notes
Degenerate/Spiking Applications
  • Degenerate PCR/RT‑PCR: rI often outperforms mixed bases for cross‑family amplification.
  • Primer design: rI substitutions can reduce unwanted structures and dimerization.
  • Microarrays: rI improves recognition of variant targets without exploding library size.
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Convertible Bases

Built-in handles for post-synthetic functionalization

Convertible RNA base analogs are designed with built-in reactive handles or temporary groups that can be selectively transformed after synthesis to introduce dyes, haptens, crosslinkers, or other conjugates. These bases streamline probe design by allowing post-synthetic functionalization at precise positions without compromising oligo yield. Popular examples include 5-ethynyl-U (EU), 5-azidomethyl-U, and O4-triazolyl-U, which enable versatile click-chemistry ligations, while amino-modified uridines support NHS-ester labeling for fluorescent and affinity tags.

Show Products & Notes
Product Description Typical Use Notes Code
5-Ethynyl-Uridine (EU) Alkyne substitution at C5 of uridine Click chemistry labeling of nascent RNA Compatible with CuAAC & SPAAC; minimal steric effect EU
5-Azidomethyl-Uridine Azide handle at U C5-CH2 Copper-free click ligation; bio-orthogonal conjugation Ideal for dye or biotin conjugation; avoids Cu toxicity AzM-U
O4-Triazolyl-Uridine O4 position linked to triazole Post-synthetic functionalization; crosslinking Versatile reactive handle for dyes & ligands O4-trz-rU
Amino-C6-Uridine (AmC6-U) Primary amine at C6 via flexible linker Conjugation with NHS-esters (dyes, peptides, haptens) Commonly used for labeling with long spacer arm AmC6U
Aminoallyl-Uridine (AmAll-rU) Allylic amine at U Dye/hapten coupling Smaller, less flexible than AmC6-U AmAll-rU
5-Iodo-Uridine Iodine substitution at C5 of uridine Photo-crosslinking; halogen substitution chemistry Activatable convertible handle for derivatization 5I-rU
5-Bromo-Uridine Bromine substitution at C5 of uridine X-ray phasing; substitution to other reactive groups Useful for structural and crystallography studies 5Br-rU
Technical Notes
  • Use mild conversion conditions to protect the RNA backbone.
  • Internal placements are better tolerated than terminal sites for bulky groups.
  • Purify after conversion (HPLC/PAGE) to remove by‑products.
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Epigenetic & Methylation Mimics

Model natural marks for binding/enzyme assays

Epitranscriptomic bases such as m6A, m1A, m5C, hm5C, f5C, ca5C, Ψ, and m7G modulate RNA stability, processing, and translation. Synthetic incorporation enables mechanistic studies with defined placements.

Show Products & Notes
Product Description Typical Use Notes Code
N6‑Methyl‑A m6A Reader/writer/eraser assays Dynamic RNA mark m6A
N1‑Methyl‑A m1A Translation/structure mapping Watson–Crick edge blocked m1A
5‑Methyl‑C m5C Epigenetics, binding modulation; Tm↑; context‑dependent m5C
5‑Methyl‑U m5U Epigenetic studies, altered binding assays Tm↑; tolerated by polymerases with a minor efficiency changes m5U
2′-O-Methyl-5-Methyl-Uridine m5U on 2′‑OMe sugar Epitranscriptomic mimic; affinity tuning; duplex stability Mild Tm↑; generally well tolerated; 5‑methyl at U behaves like rT analog [2OMe-5Me-U]
2′-O-Methyl-5-Methyl-Cytidine m5C on 2′‑OMe sugar Epigenetic studies; duplex stability; reader protein assays Tm↑; can alter protein recognition vs C; commonly used in methylation models [2OMe-5Me-C]
5‑Hydroxymethyl‑C hm5C Demethylation intermediates Hydrophilic handle hm5C
5‑Formyl‑C f5C tRNA modification studies Reactive aldehyde f5C
5‑Carboxyl‑C ca5C Advanced oxidation product Tm↓; acidic ca5C
Pseudouridine Ψ Stability/translation effects C‑glycosidic; improves folding Ψ
7‑Methyl‑G m7G (cap analog) 5′ cap modeling Terminal use typical m7G
Technical Notes
  • These marks affect protein recognition (readers), installation (writers), and removal (erasers).
  • Placement in motifs (e.g., DRACH for m6A) is key to biological interpretation.
  • High‑purity synthesis and rigorous QC recommended for quantitative biology.
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Artificial Base Pairs / Expanded Alphabet

Orthogonal pairing systems for information density

Engineered base pairs (e.g., isoC/isoG, 5‑Me‑iso‑dC/isoG, dP/dZ) can operate in RNA contexts for labeling or coding with specialized enzymes. Availability is platform‑specific—contact us to review current options.

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Product Description Typical Use Notes Code
isoC Pairs with isoG Orthogonal pairing Requires matched partner isoC
isoG Pairs with isoC Orthogonal pairing Tautomerization risk isoG
5‑Me‑iso‑dC Methylated isoC analog Improved fidelity vs isoC Stabilizes isoC–isoG 5‑Me‑iso‑dC
dP/dZ system Orthogonal pair Expanded genetic alphabet Polymerase‑dependent dP/dZ
Technical Notes
  • Internal placements typically perform better than terminal sites.
  • Use matching partner bases and compatible enzymes.
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Hapten-Tagged & Functional Bases

Built-in capture/detection tags

Hapten‑tagged bases carry small antigenic tags (biotin, DIG, DNP, fluorescein, rhodamine) for capture or immunodetection in RNA probes and assays.

Show Products & Notes
Product Description Typical Use Notes Code
Biotin‑rU / Biotin‑rC Biotin hapten on base Affinity capture/immobilization High affinity to streptavidin Bio‑rU
DIG‑rU / DIG‑rC Digoxigenin hapten ISH/FISH; immunodetection Anti‑DIG antibody detection DIG‑rU
DNP‑rU Dinitrophenol hapten Immunodetection Anti‑DNP antibodies DNP‑rU
FITC‑rU / Rhodamine‑rU Fluorophore haptens on base Fluorescence + immuno workflows Beware self‑quenching FITC‑rU
Technical Notes
  • Biotin for capture; DIG/DNP for antibody detection; FITC/Rhodamine for fluorescent readouts.
  • Use multiple tags with spacing to avoid sterics.
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Structure and Blocking Modified Bases

Control secondary structure, hybridization and nuclease interaction

Structure & blocking bases disrupt canonical pairing, introduce bulky/rigid features, or sterically block enzymatic access to control secondary structure, hybridization, and processing.

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Product Description Typical Use Notes Category
Abasic (rSpacer) Missing base; structural gap Blocks extension; lesion mimic Behaves like a gap Bulky/Steric Blocking
Spacer C3 / C9 / HEG Non‑nucleosidic spacers Prevent pairing/extension Steric block; structure control Bulky/Steric Blocking
Pyrene‑rU / Perylene‑rU Bulky aromatics Intercalating block; FRET probes Strong π‑stackers Helix‑Distorting
Pyrrolo‑rC Altered geometry Local structure probing Fluorescent readout Helix‑Distorting
4‑Thio‑U Thio substitution UV‑trap to lock structure Photo‑crosslinker Photo/Crosslinking
5‑Br‑rU / 5‑I‑rU Halogenated bases Photo‑induced crosslinking UV‑sensitive Photo/Crosslinking
Technical Notes
Applications
  • Place blockers at 3′ ends to stop extension or internally to modulate folding.
  • Use thio/halo bases for covalent trapping of transient structures.
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Crosslinking and Ligation Bases

Covalent bonding, structural probing, and bioconjugation

Cross‑linking & ligation bases include photo‑reactive thio/halo bases, psoralens, and click handles (alkynes/azides) for covalent trapping, structure mapping, and post‑synthetic conjugation.

Show Products & Notes
Product Description Typical Use Notes Category
Psoralen‑rU (C2/C6) Psoralen linked to U UV‑induced interstrand crosslinks 320–365 nm activation Intercalator/Photoadduct
4‑Thio‑U Thiolated U Photo‑crosslinking; PAR‑CLIP UV‑A reactive Photoreactive
6‑Thio‑G Thiolated G Metal coordination; crosslinking Sulfur reactivity Reactive
5‑Ethynyl‑U (EU) Alkyne handle Click ligation/labeling CuAAC/SPAAC compatible Clickable
5‑Azidomethyl‑U Azide handle Strain‑promoted click Copper‑free Clickable
5‑I‑rU / 5‑Br‑rU Halogenated bases Photocrosslink; crystallography Strong scatterers Photoreactive
Technical Notes
  • Photo‑activated cross‑linking: Psoralen, iodo, and bromo bases form covalent links upon UV irradiation.
  • Reactive handles: EU/azido‑U support click‑based conjugation to dyes, peptides, or surfaces.
  • Sulfur substitutions: s4U/s2U/6sG enable photoreactivity and metal coordination.
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Halogenated Bases

UV-induced covalent trapping

Bromine, iodine, or fluorine substitutions provide photo‑reactivity and strong X‑ray scattering, enabling cross‑linking, structural probing, and phase determination in RNA structural biology.

Show Products & Notes
Product Description Typical Use Notes Code
5‑Bromo‑rU Brominated uridine Crystallography; photocrosslinking UV‑inducible 5Br‑rU
5‑Bromo‑rC Brominated cytidine RNA structural probes Heavy atom derivative 5Br‑rC
5‑Iodo‑rU Iodinated uridine Photocrosslinking; phasing Strong scatterer 5I‑rU
5‑Iodo‑rC Iodinated cytidine RNA crystallography Heavy halogen 5I‑rC
5‑Fluoro‑rU Fluorinated uridine NMR probes; Tm tuning Small halogen; mild effects 5F‑rU
Technical Notes
  • Heavy atom derivatives (Br/I) enable X‑ray phasing.
  • Photo‑crosslinking allows mapping RNA–protein and RNA–RNA interactions.
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Intercalator Bases

Bulky base alter stability, enhance binding or act as probles

Intercalator‑modified bases carry bulky aromatic groups that insert between stacked base pairs, enhancing duplex stability and enabling fluorescence/FRET or photo‑induced crosslinking.

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Product Description Typical Use Notes Code
Psoralen‑rU (C2/C6) Psoralen on U UV interstrand crosslinking 320–365 nm activation Psor‑rU
Ethidium‑rU Ethidium dye on U Fluorescent intercalator Strong emission upon binding Et‑rU
Acridine‑rC / Acridine‑rU Acridine linked bases Stabilize duplex; probes Tm↑; strong intercalator Acr‑rC/rU
Pyrene‑rU Pyrene at U C5 Excimer/exciplex studies Environment‑sensitive Pyr‑rU
Perylene‑rU Perylene at U C5 FRET donor/acceptor Hydrophobic; internal sites Per‑rU
Anthraquinone‑rU AQ group on U Photoinduced ET Generates ROS on hv AQ‑rU
Naphthyl‑rC Naphthyl on C Stacking probes Smaller intercalator Naph‑rC
Technical Notes
  • Stability: Intercalators generally raise duplex Tm.
  • Fluorescence: Pyrene/perylene provide strong, environment‑sensitive signals.
  • Photoreactivity: Psoralen/AQ enable UV‑induced crosslinks or ET chemistry.
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Fluorescent Bases

Probing for nucleic acid dynamics

Fluorescent base analogs minimally perturb RNA structure while reporting on stacking, pairing, or conformational changes—ideal for FRET, hybridization monitoring, and RNA–protein interaction assays.

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Product Description Typical Use Notes Code
Ribo‑tC° Fluorescent C analog RNA duplex probe Pairs like C; bright ribo‑tC°
tC° Neutral tricyclic C Environment‑sensitive probe Minimal perturbation tC°
tCnitro Nitro‑substituted tricyclic C Internal fluorescent reporter High quantum yield tCnitro
Pyrrolo‑C (rC) Fluorescent cytidine Hybridization dynamics Exc. ~350 nm pyr‑rC
2‑Aminopurine (ribo) Fluorescent adenine analog Stacking/conformation Quenched in duplex 2‑AP‑r
2′-OMe-2-Aminopurine Fluorescent adenine analog folding and kinetics reporter Quenched in duplex [2OMe-2AP]
Pyrene‑rU / Perylene‑rU Aromatic fluorophores FRET/excimer probes Hydrophobic; spacing advised Pyr‑rU / Per‑rU
Technical Notes
  • Choose tricyclic C variants for bright, minimally perturbing signals.
  • 2‑AP is sensitive to stacking and useful for dynamics despite quenching.
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Related Products & Services

Explore complementary RNA technologies
siRNA

Custom synthesis and modification of small interfering RNA for gene silencing applications.

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Antisense RNA

ASO design with 2′-OMe, 2′-F, LNA and phosphorothioate linkages for stability and potency.

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Aptamers

Modified RNA aptamers with enhanced nuclease resistance and high affinity binding.

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mRNA Therapeutics

m1Ψ, m5C and cap analog incorporation for vaccine and therapeutic development.

Learn More

Design Tips

Balance affinity, specificity, and enzyme compatibility
  • Use base analogs sparingly: excess substitutions can hinder polymerases or distort structure.
  • Tune Tm intentionally: thio/halo & intercalators raise Tm; universal bases typically lower Tm.
  • Assay‑first selection: for crosslink mapping choose s4U or psoralen‑rU; for minimal fluorescence pick ribo‑tC° or pyrrolo‑C.
  • Combine with sugar/backbone edits: pair base analogs with 2′‑OMe/LNA wings and PS linkages to improve stability.

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Purification & QC

Match grade to application
  • Purification: RP‑HPLC, IE‑HPLC, PAGE; dual HPLC/PAGE available.
  • QC: LC‑MS/ESI‑MS, analytical HPLC or CE/IE, UV quantification in duplicate.
  • Documentation: CoA with yields, MW, and traceability; ISO/GLP/GMP‑aligned records on request.

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Ordering & Scales

From RUO to cGMP

Typical research scales range from 0.05–15 µmol; development 1 mg–100 gram; large‑scale multi‑gram available with full documentation. Turnaround depends on analog choice, length, and purification.

Deliverables Dry (lyo) or liquid Custom buffer Plates or vials OEM/private-label

FAQ

Are these analogs compatible with RT/PCR?

Some are—e.g., rI and certain fluorescent bases are tolerated, while bulky intercalators or heavy halogens can inhibit extension. Validate per enzyme.

Do you provide custom analogs not listed?

Yes—contact us with your target base/handle (e.g., special photo‑reactive groups or click handles) and we’ll evaluate feasibility.

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