Fluorescence and chemical reactivity as empirical indices of matrix-induced alterations in immobilized enzymes.

The fluorescence emission and chemical reactivity of soluble and Sepharose-bound leucine aminopeptidase and carboxypeptidase A were investigated and the results compared. Both natural fluorescence and the fluorescence of fluorescein-labeled enzymes were utilized. The front-surface viewing technique enables us to measure the apparent fluorescence quantum yields and the rotational relaxation times of fluorescent groups within native unbound and carrier-fixed enzymes. The chemical reactivity was probed with Ellman's reagent and iodoacetic acid. Both types of methods were found to be useful in detection and quantitation of matrix-induced alterations in immobilized enzymes.