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. Author manuscript; available in PMC: 2012 Nov 15.
Published in final edited form as: Bioorg Med Chem. 2011 Apr 16;19(22):6633–6638. doi: 10.1016/j.bmc.2011.04.024

Figure 5.

Figure 5

Qualitative time course of acetyl- and benzoyl-EncC incubated with EncL at room temperature. Shown are the deconvoluted LTQ-orbitrap mass spectra of the reaction mixture before the addition of EncL (−EncL) and at the indicated times after the addition of EncL. Indicated in Da are the theoretical (Calc) and experimentally observed (Obs) monoisotopic masses of holo-EncC, acetyl-EncC, and benzoyl-EncC. The acetyl-loaded form of EncC was depleted already 30 seconds after the addition of EncL with a corresponding increase of holo-EncC. In contrast, benzoyl-EncC is hydrolyzed relatively slowly. The concentration of each acyl-EncC form was ~20 μM, while the concentration of EncL was ~0.5 μM. Some amount of apo-EncC (calculated mass: 12086.3 Da, observed 12086.1 Da) was clearly visible (vertical arrow) in the control sample without EncL but not in the other samples, probably because of phosphopanteteinylation of apo-EncC by Sfp with residual acyl-CoA. Masses of other strong bands visible in the spectra are consistent with phosphate adducts (+98 Da), potassium adducts (+38), and oxidized forms (+16) of the main species indicated, as shown by the horizontal arrows.