The influence of sodium trichloroacetate on the tryptophan fluorescence of sarcoplasmic reticulum ATPase.
The chaotropic anion trichloroacetate quenches the tryptophan fluorescence of the sarcoplasmic reticulum calcium transport ATPase. Half-maximum quenching was observed at 50 mM trichloroacetate. In contrast to native preparations, in trichloroacetate-treated sarcoplasmic reticulum vesicles a decrease of the tryptophan fluorescence is observed on addition of millimolar concentrations of calcium. It is concluded that trichloroacetate renders the tryptophan fluorescence of the ATPase sensitive to the occupancy of its low-affinity sites.
D000818:Animals; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D007700:Kinetics; D011485:Protein Binding; D011487:Protein Conformation; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D014238:Trichloroacetic Acid / Q000494:pharmacology*; D014364:Tryptophan / Q000032:analysis*
D014238:Trichloroacetic Acid; D014364:Tryptophan; D000252:Calcium-Transporting ATPases