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. 2016 Jun 28;5(5):802–818. doi: 10.1002/mbo3.371

Figure 1.

Figure 1

MALDI‐MS detection of 5,10‐CH = THF polyglutamates in TFA‐treated L. reuteri cell pellets. Peaks indicating the presence of 5,10‐CH = THF polyglutamate (arrows, MGlun) are marked for strain (A) 6475 and (B) 55730. The subscripted number (n) after MGlu indicates the number of glutamate residues present in the polyglutamate tail, not counting the intrinsic glutamate of folic acid. (C) MALDI ion trap MS/MS fragmentation analysis of MGlu5 at m/z 1101.4 confirms the presence of a folate compound, consistent with the lightest MS/MS fragment ion at m/z values 327.1. (D) Inactivation of folC2 in 6475 inhibited the production of 5,10‐CH = THF compounds as monitored by MALDI MS. (E) The 6475::folC mutant produced 5,10‐CH = THF (structure depicted), but no 5,10‐CH = THF polyglutamates of any chain length. The unidentified ion at m/z 932.4 was consistently observed after TFA treatment of all L. reuteri cell pellets. All spectra were scaled to comparable maximum intensity levels. TFA, trifluoroacetic acid; 5,10‐CH = THF, 5,10‐methenyltetrahydrofolic acid.