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The deprotection of Lys(Mtt) revisited
L Bourel1, O Carion, H Gras-Masse
1UMR 8525 CNRS-Université de Lille 2, Institut de Biologie et Institut Pasteur de Lille, France. line.bourel@pasteur-lille.fr
Abstract:
The selective deprotection of Lys(Mtt)-containing peptidyl resins was successfully monitored by RP-HPLC using very short linear gradients. RP-HPLC analyses of the acidic filtrates also revealed the partial cleavage of the Trt groups and of the peptide-resin bond. The absorbance of the Mtt carbocation at 470 nm is only twice that of the Trt cation. Thus, the UV monitoring at 470 nm seems to be inappropriate, especially at the end of the deprotection, when the Mtt and the Trt levels are comparable.
Insights
Selective deprotection of Lys(Mtt) peptidyl resins was monitored using RP-HPLC. UV monitoring at 470 nm is inappropriate due to comparable Mtt and Trt cation absorbance, hindering accurate deprotection assessment.
Area of Science:
- Organic Chemistry
- Analytical Chemistry
- Peptide Synthesis
Background:
- Peptide synthesis relies on selective protecting group strategies.
- Lysine side-chain protection is crucial for complex peptide assembly.
- Monitoring deprotection steps is essential for synthesis success.
Purpose of the Study:
- To evaluate RP-HPLC for monitoring selective Lys(Mtt) deprotection.
- To assess the suitability of UV monitoring at 470 nm for Mtt deprotection.
- To identify potential issues during selective deprotection of peptidyl resins.
Main Methods:
- Selective deprotection of Lys(Mtt)-containing peptidyl resins.
- Monitoring deprotection using Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC).
- Analysis of acidic filtrates and UV absorbance of carbocations.
Main Results:
- RP-HPLC successfully monitored selective Lys(Mtt) deprotection with short gradients.
- Partial cleavage of Trt groups and peptide-resin bonds was observed.
- UV monitoring at 470 nm is unsuitable due to similar Mtt and Trt cation absorbance.
Conclusions:
- RP-HPLC is a viable method for monitoring selective Mtt deprotection.
- UV monitoring at 470 nm is unreliable for assessing Mtt deprotection completion.
- Careful selection of monitoring techniques is vital in solid-phase peptide synthesis.