Surveyor substrates: energy-transfer gauges of active center topography during catalysis

An approach is described for the simultaneous measurement of catalysis, the distance from an active-site moiety to fluorescent substrate moieties of an enzyme substrate complex, and the microenvironment of such substrate groups. It is illustrated by means of a three-component energy transfer relay system, consisting of cobalt carboxypeptidase, its fluorescent dansylated peptide substrates, and tryptophanyl residues of the enzyme. The mode of procedure can be applied generally to yield conjoint information on functional and structural aspects of active centers of enzymes.