Fig. 3: Dissecting the reaction mechanism between alkyl diazirine and protein residues.
a The reaction between alkyl diazirine (SDA) and a protein residue in AXA tripeptide (HY, inset). b The generation of SDA-HY can be attributed to five elementary processes, b1, b2, b3, b4, and c. The theoretical hypothetical curves of these processes are plotted with the irradiation time t of 1 min. c Fitting the experimental data of SDA-HY production over optical power density \(\left[{hv}\right]\) allows the determination of the relative contribution of the elementary processes. Shown here are the fitting results for ASA (red) and AIA (blue) tripeptides, with Pearson’s correlation R2 of 0.99 for both. Error bar represents 1 S.D. from 3 separate measurements with the averaged values shown as open circles. d The relative involvement of diazo B or carbene C intermediate for the general SDA-HY can be assessed based on the value of \(({b}_{1}+{b}_{2}+{b}_{3}+{b}_{4}-c)\), which can be positive or negative, respectively. Error bar represents 1 S.D. from curve fitting (Supplementary Fig. 6). e The relative yield of SDA-HY can be evaluated by the decrease of MS signal of AXA tripeptide. Polar residues that are preferentially targeted by diazo intermediates are colored red, and non-polar residues that are preferentially targeted by carbene intermediates are colored blue. Error bar represents 1 S.D. from 3 separate measurements (open circles).
