Fig 2. Absorption spectra from 250–950 nm of GPR and mutants containing MMAR chromophore at different pHs.

Spectra were recorded at room temperature of GPRs reconstituted into E. coli polar lipids membrane vesicles and used to produce fully hydrated multilamellar films deposited on BaF₂. All spectra were scaled using the 281 nm absorption band. DNFS is abbreviation for the mutant D212N/F234S and MR for MMAR chromophore. Absorption (OD) scale shown is for the GPR-DNFS:MR film at pH 5.