Issue 1, 2007
From the journal:

Molecular BioSystems

MALDI-TOF mass spectral analysis of siRNA degradation in serum confirms an RNAse A-like activity†

John J. Turner,a   Simon W. Jones,b   Sterghios A. Moschos,c   Mark A. Lindsayc  and  Michael J. Gait*a  

* Corresponding authors

a Medical Research Council, Laboratory of Molecular Biology, Hills Road, Cambridge, UK
E-mail: mgait@mrc-lmb.cam.ac.uk
Fax: +44 (0)1223 402 070
Tel: +44 (0)1223 248 011

b AstraZeneca R & D, Respiratory and Inflammation Research Area, Alderley park, Macclesfield, Cheshire, UK

c Biopharmaceutics Research Group, Airways Disease, National Heart and Lung Institute, Imperial College, London, UK

Abstract

Synthetic siRNA duplexes are used widely as reagents for silencing of mRNA targets in cells and are being developed for in vivo use. Serum stability is a major concern if siRNA is to be used for therapeutic delivery within blood circulation. We have developed the use of MALDI-TOF mass spectrometry as a rapid and convenient analytical tool to identify the most vulnerable sites within siRNA to serum degradation. Using this approach, we found that one siRNA duplex (Dh3) with UpA sequences close to one end was particularly vulnerable to rapid cleavage. This produced a fragment of mass consistent with the presence of a 2′,3′-cyclic phosphate that was slowly hydrolysed to a 2′-(3′-)phosphate on extended incubation. Substitution of these sites with 2′-O-methyl U residues prevented cleavage and confirmed that the major pathway for initial degradation is via cleavage by an RNAse A-like activity. Mass spectral analysis was used to follow the serum degradation of siRNA over more prolonged periods to show the accumulation of many fragments, almost all showing cleavage following pyrimidine nucleoside residues. Overall, the MALDI-TOF mass spectral analysis technique should prove useful for preliminary screening of the serum stability of siRNA duplexes and for identification of the most vulnerable cleavage sites.

Graphical abstract: MALDI-TOF mass spectral analysis of siRNA degradation in serum confirms an RNAse A-like activity

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Article information

DOI
https://doi.org/10.1039/B611612D
Article type
Paper
Submitted
11 Aug 2006
Accepted
30 Oct 2006
First published
20 Nov 2006

Mol. BioSyst., 2007,3, 43-50

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MALDI-TOF mass spectral analysis of siRNA degradation in serum confirms an RNAse A-like activity

J. J. Turner, S. W. Jones, S. A. Moschos, M. A. Lindsay and M. J. Gait, Mol. BioSyst., 2007, 3, 43 DOI: 10.1039/B611612D

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