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. Author manuscript; available in PMC: 2020 Dec 21.
Published in final edited form as: Org Lett. 2018 Aug 20;20(17):5344–5347. doi: 10.1021/acs.orglett.8b02265

Figure 4.

Figure 4.

Organocatalyzed protein modification. (a) Ligation of N-terminal myoglobin aldehyde 15 (0.15mM) with different ketones (6, 17, 18 (10 mM)) using either proline (b, c) or O-tBu-Thr (d, e) (100 mM) as catalysts in 25 mM phosphate buffer (pH 7.5) and upto 15% DMSO at 37°C. Deconvoluted ESI-MS spectra of (b) unconjugated myoglobin aldehyde 15, (c) myoglobin hydroxyacetone bioconjugate 16 generated by reaction with 6, (d and e) myoglobin-peptide bioconjugates 19 (60%) and 20 (40%) generated by reaction with peptide ketones GIRVF 17 and ACF 18.