Skip to main content
. Author manuscript; available in PMC: 2017 Sep 15.
Published in final edited form as: Chembiochem. 2016 Sep 7;17(18):1738–1751. doi: 10.1002/cbic.201600266

Figure 14.

Figure 14

Analysis of the molecular forms detected for GB1 Val39Met grown in the Met auxotroph RF11. Molecular species: GB1 Val39Met calculated mass is 6181 Da and detected is 6180 Da; GB1 Val39SeM calculated mass is 6228 Da and detected is 6227 Da. Other putative assignments are: GB1 Val39CF3Sem calculated molecular mass is 6282 Da, GB1 Val39Met with a loss of a methyl group is 6166 Da, GB1 Val39Met with a loss of water is 6161 Da; and GB1 Val39Met with acetylation or an acetonitrile adduct is 6221 Da. (A) Deconvoluted mass spectrum showing GB1 Val39Met grown with solely 22 μM Met. (B) Deconvoluted mass spectrum showing GB1 Val39Met grown with 22 μM Met and 200 μM TFSeM. (C) Deconvoluted mass spectrum showing GB1 Val39Met grown with solely 200 μM TFSeM. (D) ESI-MS spectrum of the peptide QYANDNG(SeM)DGEWTYDDATK derived from trypsin digestion of the sample shown in panel B. The observed isotope pattern matches the calculated one (the predicted pattern is not shown).