Using Novel RNases to Measure 5’ Cap and Poly(A) Tail Modifications during Oligonucleotide Mapping LC-MS of mRNA

Significance of the Topic

The rapid expansion of RNA therapeutics demands advanced analytical methods to confirm sequence integrity and modification patterns of sgRNA and mRNA molecules. Comprehensive mapping enhances quality control and regulatory compliance for novel drugs.

Aims and Study Overview

This study evaluates the use of complementary RapiZyme RNases MC1 and Cusativin for oligonucleotide mapping LC-MS to characterize 5′ cap structures and poly(A) tails of messenger RNA in a single digest workflow. The goal is to increase sequence coverage and detect end-modifications without additional sample preparation.

Used Instrumentation

• RapiZyme MC1 and Cusativin RNases for targeted RNA hydrolysis
• ACQUITY Premier OST C18 column (2.1 x 150 mm, 1.7 μm) at 60 °C
• ACQUITY Premier LC system coupled to Xevo G3 MS or BioAccord MS
• Negative ESI-MS detection (m/z 400–5000, cone voltage 40 V, 2 Hz)

Methodology

Sample preparation involved denaturing sgRNA or mRNA in ammonium acetate buffer followed by enzymatic digestion (30 °C, 30 min) with optimized RNase units. Digestion was quenched by heat inactivation. Oligonucleotides were separated by gradient elution using HFIP/DPA mobile phases and analyzed by high-resolution LC-MS. Data acquisition and processing employed waters_connect software and in silico mapping tools.

Main Results and Discussion

• MC1 and Cusativin exhibit complementary cleavage specificities, producing unique oligonucleotide masses for enhanced sequence discrimination
• Partial overlapping digestion products improve redundancy and achieve >95% MS1 sequence coverage including 5′ and 3′ ends
• High reproducibility across enzyme batches simplifies workflow validation
• Direct detection of cap1, incomplete caps and uncapped species without further sample prep
• Poly(A) tail length distribution characterized from the same digest using intact mass analysis

Benefits and Practical Applications

Combining RNases with LC-MS mapping provides a rapid, additive-free protocol for comprehensive RNA therapeutic characterization. The approach supports identity confirmation, purity assessment and end-modification profiling critical for quality assurance in research and production settings.

Future Trends and Opportunities

Advances may include new enzyme pairs for deeper modification mapping, automated sample handling, improved informatics pipelines and integration with regulatory workflows. Expanded cap and tail profiling will further streamline mRNA drug development and release testing.

Conclusion

This work demonstrates that RapiZyme MC1 and Cusativin enable detailed oligonucleotide mapping of sgRNA and mRNA in a single digest, capturing full-length sequence, 5′ caps and poly(A) tails. The method offers robust troubleshooting and high confidence in therapeutic RNA analysis.

References

1. Thakur et al. (2022) Int J Mol Sci 23: 7021.
2. Jumper et al. (2021) Nature 596: 583.
3. Sehnal et al. (2021) Nucleic Acids Research 49: W431.
4. Addepalli et al. (2024) Waters Application Note 720008539.
5. Doneanu et al. (2025) Waters Application Note 720008677.
6. Menneteau et al. (2025) LCGC International 2:26.