Fig. 4: Chemoselective labeling of myoglobin using chloramine-T analogs.
From: Copper(I)-nitrene platform for chemoproteomic profiling of methionine
a Labeling of methionine containing pentapeptide Fmoc-VKQMK with various chloramine-T analogs containing electron withdrawing and electron releasing groups using CuNiP. Electron-donating groups (Me or OMe) gave better product:sulfoxide ratio (2a; Me, 87:13; 2b; OMe, 72:28) compared to their electron-withdrawing counterparts (2c; Cl, 66:34; 2d; -COOH, 38:62; 2e; -NO2, 37:63; 2f; 3,5-di-F, 24:76; 2g; -CF3, 54:46). b Screening of electron-donating and electron-withdrawing chloramine-T analogs on myoglobin. c Calculated Mulliken population analysis and Natural Bond Orbital (NBO) analysis on various chloramine-T probes showing electron donating groups (blue) exhibit high efficiency for modifying methionine to sulfonyl sulfimide conjugate than electron withdrawing groups (red), due to an increased electron density on nitrene nitrogen followed by sulfimidation. Figure 4, created with BioRender.com, released under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International license” (Agreement number: NZ26NYBOZJ).
