Skip to main content
. Author manuscript; available in PMC: 2022 Apr 28.
Published in final edited form as: Biochemistry. 2022 Apr 5;61(8):689–702. doi: 10.1021/acs.biochem.1c00774

Figure 5.

Figure 5.

LC-MS detection of products in single-turnover reactions of BesC (0.25 mM) after incubation at 22 °C with Fe(II) (0.50 mM) and 4-thia-Lys (0.25 mM) in 100 mM sodium HEPES, pH 7.5, 100 mM NaCl, 5% (v/v) glycerol. Single-ion monitoring (SIM) of a control reaction without enzyme shows a large peak for 4-thia-L-Lys at 165 m/z (rear trace) but no peaks at either 183 or 181 m/z. In the presence of natural abundance O2 (16O2), the substrate is mostly consumed, and SIM traces at 181 m/z reveal a new peak with a shift of +16 m/z compared to 4-thia-Lys. Reactions with 18O2 show a mass shift of +18 m/z (at 183 m/z), consistent with the incorporation of an oxygen atom into the product.