Fluorescence of 1,8-anilinonaphthalene sulfonic acid bound to proteins and to lipids of sarcolemma.

Relative contributions to fluorescnece of 1,8-anilinonaphthalene sulfonic acid-sarcolemma by 1,8-anilinonaphthalene sulfonic acid bound to proteins and to lipid were assessed on the basis of fluorescence lifetime and steady-state emission spectra. The lifetime spectrum of lipid-poor proteins prepared from sarcolemma had a major time constant of 16 ns; that of lipids extracted from sarcolemma had a major time constant of 7 ns and a minor one of 4 ns. In sarcolemma, components having all three time constants were observed with weighting factors 0.33, 0.6 and 0.07, respectively, indicating the fraction of 1,8-anilinonaphthalene sulfonic acid bound to protein and to lipid. Steady-state emission spectra of 1,8-anilinonaphthalene sulfonic acid-sarcolemma were resolved into and resynthesized from contributions by 1,8-anilinonaphthalene sulfonic acid bound to proteins and to lipids. The latter was at least two thirds of total 1,8-anilinonaphthalene sulfonic acid bound. Results of analyses of spectra obtained with various concentrations of sarcolemma and 1,8-anilinonaphthalene sulfonic acid suggest that the proteins have a higher affinity, but only about half the binding capacity for 1,8-anilinonaphthalene sulfonic acid as do lipids.