Intrinsic tryptophan phosphorescence as a marker of conformation and oxygen diffusion in purified cytochrome oxidase

FEBS Letters

Papp, Sandor²  King, Tsoo E.¹  Vanderkooi, Jane M.² 

[1] Institute for Structural and Functional Studies, University of City Science Center, Philadelphia, PA 19104, USA;Department of Biochemistry and Biophysics, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA

关键词: Cytochrome oxidase;    Oxygen;    Phosphorescence;    Trytophan;   

DOI  :  10.1016/0014-5793(91)80566-L

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Cytochrome oxidase exhibits phosphorescence from trytophan in aqueous solution in the absence of oxygen. The lifetime for the resting reduced enzyme suspended in Tween-20 is around 30 ms at pH 8. The lifetime is longest between pH 7 and 8 and decreases with lowering of pH. Oxygen quenches the phosphorescence with a Stern-Volmer quenching constant of ∼5 × 10⁷ M⁻¹ s⁻¹ at 5°C whereas cytochrome c has no effect. We interpret these results to indicate that room temperature tryptophan phosphorescence arises from trytophan(s) in structured region(s) remote from the hemes and that the protein does not impose a significant barrier for the diffusion of oxygen.

【 授权许可】

Unknown