Cooperative Effects in Binding by Bovine Serum Albumin. II. The Binding of l-Anilino-8-naphthalenesulfonate. Polarization of the Ligand Fluorescence and Quenching of the Protein Fluorescence

Gregorio Weber, Ezra Daniel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The decrease in the polarization of the fluorescence of anilinonaphthalenesulfonate adsorbed upon bovine serum albumin with the average number bound is found to be due solely to electronic energy transfer among the ligand molecules. A descriptive theory of this phenomenon is developed using two simplifying assumptions: (1) random distribution of the ligand molecules among the protein binding sites. (2) A single transfer of the excited state is responsible for the depolarization. Under these assumptions, a “system of equivalent oscillators” may be defined which best fits the experimental data. The equivalent system for the albumin-anilinonaphthalenesulfonate case is one in which the average distance between a pair of binding sites is 21 A and the average angle between two emission oscillators is 33°. The polarization data show the existence of cooperative features in the binding o pH 5 by comparison with that at pH 7, a phenomenon already seen in the titration curves. The quenching of tryptophan fluorescence by transfer of the excited state to the anilinonaphthalenesulfonate may be used to reach a similar conclusion. In addition, it leads to an estimate of ca. 33 A for the average distance between the partners involved in this transfer.

Original languageEnglish
Pages (from-to)1900-1907
Number of pages8
JournalBiochemistry
Volume5
Issue number6
DOIs
StatePublished - 1966
Externally publishedYes

Fingerprint

Dive into the research topics of 'Cooperative Effects in Binding by Bovine Serum Albumin. II. The Binding of l-Anilino-8-naphthalenesulfonate. Polarization of the Ligand Fluorescence and Quenching of the Protein Fluorescence'. Together they form a unique fingerprint.

Cite this