Conformational heterogeneity in pyranose 2-oxidase from Trametes multicolor revealed by ultrafast fluorescence dynamics

► The fluorescence dynamics of P2O enzyme was elucidated in terms of two different conformers. ► Dominant quenching process was ascribed to photoinduced ET reaction from Trp168 to the excited isoalloxazine. ► The conformers 1 and 2 have different static dielectric constants (ɛ1 ∼ 3.25 and ɛ2 ∼ 5.93, respectively). ► The protein quaternary structure is responsible for the observed conformational heterogeneity with different dielectric constants.