Abstract
The ATPase of the thermophilic bacterium PS3, TF0F1 and its subunits has been isolated and their absorption and fluorescence spectra have been measured. The following results were obtained:
(1) The tryptophan content of the subunits was determined spectroscopically.
(2) Although tryptophan (Trp) and tyrosine (Tyr) are found in TF1, the fluorescence spectrum of native TF1 and its subunits is dominated by Tyr fluorescence; this is in contrast to other proteins.
(3) Among (native) TF1 and its subunits only TF1 and the u-subunit show a weak fluorescence of Trp, which is blue-shifted, indicating a location in a strongly hydro-phobic environment.
(4) TF0 fluorescence is dominated by the strong Trp fluorescence.
(5) TF0F1 fluorescence is also dominated by the Trp residues. Additionally, its fluorescence is higher than the sum of the isolated TF0 and TF1, indicating marked changes in the microenvironment of the fluorescing aminoacids upon binding of TF1 to TF0.
