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. Author manuscript; available in PMC: 2018 Nov 17.
Published in final edited form as: ACS Chem Biol. 2017 Oct 18;12(11):2849–2857. doi: 10.1021/acschembio.7b00614

Figure 3.

Figure 3

Gel-based analysis of probes to examine ring geometry (2 and 3) and side chains that act as substrate mimetics (5 and 6). (a) TAMRA-functionalized probes. (2R,3S)-β-lactone (2T) and (2S,3R)-β-lactone (3T) showed different labeling profiles. The addition of glycine between the lactone and fluorophore group (10T) altered the labeling profile to include PBP2b but not PBP2a. The D-Ala-based probe (amino acid stereochemistry found in stem peptide; 5T) labeled all HMW PBPs, while the L-Ala-functionalized molecule was more selective (6T; PBP1b and PBP2x). (b) Fluorescein-functionalized probes. PBP labeling with 2FL and 6FL is comparable to the TAMRA probes. The D-Ala-based probe (5FL; PBP1b and PBP2x) tagged fewer PBPs than the TAMRA analog (5T). All probes were assessed at 5 μg/ mL.