Reactive trityl derivatives: stabilised carbocation mass-tags for life sciences applications
Abstract
The rational design of novel triarylmethyl (trityl)-based mass tags (MT) for mass-spectrometric (MS) applications is described. We propose a "pKR+ rule" to correlate the stability of trityl carbocations with their MS performance: trityls with higher pKR+ values ionise and desorb better. Trityl blocks were synthesised that have high pKR+ values and are stable in conditions of MS analysis; these MTs can be ionised by matrix as well as irradiation with a 337 nm nitrogen laser. 13C-Labelled tags were prepared for MS quantitation applications. Moreover, the tags were equipped with a variety of functional groups allowing conjugation with different functionalities within (bio)molecules to enhance the MS characteristics of the latter. The MS behaviour of model polycationic trityl compounds with and without the matrix was studied to reveal that poly-trityl clusters are always singly charged under the (MA)LDI-TOF conditions. Several peptide-trityl conjugates were prepared and comparisons revealed a beneficial effect of trityl tags on the conjugate detection in MS. Trityl compounds containing para-methoxy- and dimethylamine groups, as well as a xanthene fragment, showed considerable enhancement in MS detection of model peptides; thus they are promising tools for proteomic applications. Dimethoxytrityl derivatives allow one to distinguish between Arg- and Lys-containing peptides. Maleimido trityl derivatives are suitable for the efficient derivatisation of thiol-containing peptides in pyridine.
Additional Information
The journal is © Royal Society of Chemistry 2008. Received 23rd June 2008, Accepted 1st October 2008. First published on the web 10th November 2008. The authors are grateful to Susan Wheeler, Claire Abrahams, Zakhar O. Shenkarev, Larisa V. Gruzintseva for useful discussions and helpful advice. NMR spectra were kindly provided by the Shemyakin–Ovchinnikov Institute NMR Spectrometry Facility (registry No. 98-03-08), high resolution mass spectra were kindly provided by the Oxford University Mass Spectrometry Facility. Electronic supplementary information (ESI) available: Synthetic procedures for compounds 4a–f, 5a–k, 7a–j, 8, 10f,g,h, 11a,b, 12a–h, 13a,c, 15a,c–h, 16a,b, 17c,d, 18, 19, 20, 21, 22b,c, 23b,d, 24d, 27b, 28d–h, 29, 31, 34, 35, 36, 37, 38, 39, 42, 43, 44, 45, 54, 55 and 56. See DOI: 10.1039/b810600bAttached Files
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Additional details
- Eprint ID
- 12910
- Resolver ID
- CaltechAUTHORS:USTobc08
- Created
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2009-01-15Created from EPrint's datestamp field
- Updated
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2021-04-09Created from EPrint's last_modified field