Tryptophan Fluorescence Changes Related to Ca(2+)-ATPase Function.

Fluorescence measurements as monitored with either extrinsic or intrinsic probes constitute important ways with which to study the molecular properties of macromolecules. With high-quality spectrofluorimeters, it is, e.g., possible kinetically to follow local conformational changes, induced by ligands and inhibitors, with a sensitivity that is unsurpassed by any other physicochemical technique. We demonstrate here with Ca(2+) and two specific inhibitors of SERCA how this can be done by measurements of the intrinsic fluorescence of the tryptophan residues of SERCA.