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In the first batch, we got 400 mg of N<sup>ε</sup>-L-cysteinyl-L-lysine trifluoroacetic acid salt and in the second batch 500 mg. This correspond to 0.84 mmol for the first batch and 1.05 mmol for the second batch. This equals to the half of the yield of Nguyen et al. (2011) with 900 mg and 1.89 mmol. | In the first batch, we got 400 mg of N<sup>ε</sup>-L-cysteinyl-L-lysine trifluoroacetic acid salt and in the second batch 500 mg. This correspond to 0.84 mmol for the first batch and 1.05 mmol for the second batch. This equals to the half of the yield of Nguyen et al. (2011) with 900 mg and 1.89 mmol. | ||
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+ | Nguyen, D.P., Elliott, T., Holt, M., Muir, T.W., Chin, J.W., 2011. Genetically Encoded 1,2-Aminothiols Facilitate Rapid and Site-Specific Protein Labeling via a Bio-orthogonal Cyanobenzothiazole Condensation. J. Am. Chem. Soc. 133, 11418–11421. doi:10.1021/ja203111c | ||
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Revision as of 09:08, 20 September 2017
Fusing
Synthesis of Nε-L-cysteinyl-L-lysine
Figure 1: Schematic reaction of the synthesis of Nε-L-cysteinyl-L-lysine fluoroacetatic acid salt (Nguyen et al., 2011).
The unprotected carboxyl group of the cysteine (red) and the unprotected amino group of the lysine (green) are highlighted.
Coupling reaction of N-Boc-L-lysine-O-methyl ester and N-Boc-L-cysteine-S-Trt
Table 1: List of used reactants and solvents for the coupling.
In both batches, we used the same quantity of reactants and solvents for the coupling reaction.
Figure 2: Result of the TLC analysis after the coupling reaction.
A: N-Boc-L-lysine-O-methyl ester; B: N Boc L cysteine-S-Trt; C: N-Boc-L-lysine-O-methyl ester, N Boc L cysteine-S-Trt and the reaction mixture after the coupling reaction; D: the reaction mixture after the coupling reaction.
Figure 3: Nuclear magnetic resonance (NMR) analysis result for the purified reaction mixture after the coupling reaction.
The signals for the hydrogen bonds of the protecting groups were highlighted because they are characteristic for the estimated product – N-Boc-L-lysine[Nε-(N-Boc-L-cysteine-S-Trt)]-6-methyl ester.
Removing the methyl ester of the N-Boc-L-lysine[Nε-(N-Boc-L-cysteine-S-Trt)]-6-methyl ester
Table 2: List of used reactants and solvents for the reaction to remove methyl ester of the first and the second batch.
Figure 4: Result of the TLC analysis after removing the methyl ester.
KC2: the reaction mixture after the coupling reaction; KC3: the reaction mixture after removing the methyl ester.
Removing tert-Butyloxycarbonyl protecting group (Boc) and Triphenylmethane (Trt) of the N-Boc-L-lysine[Nε-(N-Boc-L-cysteine-S-Trt)]
Table 3: List of used reactants and solvents for the reaction to remove Boc and Trt of the first and the second batch.
Figure 5: NMR analysis result for the purified Nε-L-cysteinyl-L-lysine trifluoroacetatic acid salt.
All peaks of compounds with hydrogen atoms of the Nε-L-cysteinyl-L-lysine were highlighted because they are characteristic for this molecule.
In the first batch, we got 400 mg of Nε-L-cysteinyl-L-lysine trifluoroacetic acid salt and in the second batch 500 mg. This correspond to 0.84 mmol for the first batch and 1.05 mmol for the second batch. This equals to the half of the yield of Nguyen et al. (2011) with 900 mg and 1.89 mmol.