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. Author manuscript; available in PMC: 2018 Oct 20.
Published in final edited form as: ACS Chem Biol. 2017 Sep 8;12(10):2598–2608. doi: 10.1021/acschembio.7b00479

Figure 4.

Figure 4

Hydrolysis of precolibactin thioester SNAC derivatives with ClbQ. (A) LC-MS based assay showing hydrolysis of a linear precolibactin SNAC thioester (26) catalyzed by WT ClbQ and partial thioester hydrolysis by the S78A mutant. (B) Extracted ion chromatograms (EIC) EIC+ = 467.30 ± 0.01 (top) and 398.33 ± 0.01 (bottom), corresponding to 26 and the hydrolyzed and cyclized product precolibactin 19, respectively. (C) LC-MS extracted ion chromatogram (EIC) traces displaying the hydrolysis of compound 20 catalyzed by recombinant ClbQ and not by ClbQ S78A (middle). EIC+ = 444.28 ± 0.01 and 343.28 ± 0.01, corresponding to SNAC thioester 20 and the hydrolyzed product precolibactin 1, respectively. (D) LC-MS extracted ion chromatogram (EIC) traces displaying no hydrolysis of cyclized precolibactin 27. EIC+ = 449.28 ± 0.01 [M + H]+2, corresponding to SNAC thioester 27.