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. 2021 Mar 9;12(2):e03637-20. doi: 10.1128/mBio.03637-20

FIG 3.

FIG 3

Retention time matching of V. fischeri biofilm-up extract on a chiral column indicates that the configuration of cyclo(His-Pro) in the microbial extract is stereoisomer cHP-3, cyclo(d-His-l-Pro). (A) Structures of all stereoisomers of cyclo(His-Pro). (B) Retention times of all synthesized stereoisomers: cHP-3 (24 min), cHP-2 (30 min), cHP-1 (33 min), and cHP-4 (44 min). A cellulose-B column was used to retain stereoisomers using 13:87 isopropyl alcohol (IPA):hexanes over 60 min at 2 ml/min. (C) A peak at 26 min was observed in the biofilm-up extract (light blue trace) and the area under the curve (AUC) measured 3,335. When coinjected with cHP-3 (dark blue trace), the peak at 26 min increased in AUC to 11,055, indicating the presence of cHP-3 in the biofilm-up extract. UV-vis was monitored at 214 nm.