Resolution of Tryptophan–ANS Fluorescence Energy Transfer in Apomyoglobin by Site-directed Mutagenesis¶

摘要: Resonance energy transfer between tryptophanyl residues and the apolar fluorescent dye 1-anilino-8-naphthalene sulfonate (ANS) occurs when fluorophore is bound to native folded sperm whale apomyoglobin. The individual contribution of two (W7 W14, both located on A-helix protein) was resolved by measuring tryptophan–ANS efficiency for ANS–apomyoglobin complexes formed wild-type protein mutants containing one or no residues, i.e. W7F, W14F W7YW14F. W14 residue found be higher than that W7, thus indicating acts as main donor in complex. This suggests plane anilinonaphthalene ring extrinsic has a spatial orientation similar and, hence, heme group holoprotein.