Amino-hexynyl-pApG
Capping Initiator for 5′-end mRNA labeling via NHS Ester Chemistry

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Product Overview
Amino-hexynyl-pApG is a chemically synthesized capping initiator designed for site-specific 5′-end modification of mRNA during in vitro transcription (IVT). Upon incorporation at the 5′-end, this dinucleotide analog introduces a primary amine functional group, enabling bio-orthogonal labeling of capped mRNA through NHS ester-based conjugation.
While it does not serve as a traditional cap structure that promotes ribosome recruitment, Amino-hexynyl-pApG enhances mRNA stability and maintains a level of translation efficiency that is superior to uncapped RNA. It also functions as a versatile reporter, supporting a wide range of chemical modifications at the 5′-terminus.
Addressing a key limitation in mRNA labeling
Conventional mRNA modification strategies are predominantly focused on the 3′-end, where enzymatic addition of functional groups enables bioconjugation. However, targeted 5′-end modifications have remained limited due to the complexity of preserving cap structure and functionality.
Amino-hexynyl-pApG offers a direct and efficient solution for 5′-end functionalization of enzymatically capped mRNA without disrupting the transcript’s integrity, allowing for new experimental and therapeutic capabilities.
Benefits & Applications
- Introduces a primary amine at the mRNA 5′-end
- Enables site-specific labeling via NHS ester conjugation
- Compatible with enzymatically capped mRNA
- Useful in fluorescent tagging, surface immobilization, and targeted delivery
- Expands options for dual-end labeling (5′ and 3′)
- Supports development of RNA therapeutics, including cell-specific targeting
Use Cases
- Fluorescent and affinity labeling of synthetic mRNA for imaging and tracking
- Conjugation of peptides, ligands, nanoparticles, or biotin via NHS esters
- Engineering targeted mRNA constructs for delivery or replacement therapies
- Investigating mRNA structure–function relationships or RNA–protein interactions
Summary
Amino-hexynyl-pApG provides researchers with a powerful and flexible tool for site-selective modification of the mRNA 5′-end. By enabling primary amine-mediated conjugation through NHS ester chemistry, it unlocks new potential in mRNA labeling, imaging, and therapeutic development — complementing traditional 3′-modification strategies and advancing the field of synthetic RNA engineering.
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Molecular Formula
C26H39N11O14P2 (free acid)
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Shelf Life
12 months unopened after receipt
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Storage Conditions
-20 °C, dark, dry
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Molecular Weight
791.60 g/mol (free acid)
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Purity
≥ 95% (HPLC)
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Physical State
colorless solution (10 mM)
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CAS Number
n.a.
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Absorption (max)
λmax = 256 nm
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Ɛ (max)
25.050 cm-1M-1
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Molecular Formula