Open AccessBinding of 1‐Anilinonaphthalene‐8‐Sulfonic Acid to α‐crystallin
Author(s) -
Stevens Arthur,
Augusteyn Robert C.
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00792.x
Subject(s) - chemistry , fluorescence , binding site , protein subunit , sulfonic acid , biophysics , yield (engineering) , crystallography , biochemistry , biology , organic chemistry , materials science , physics , quantum mechanics , gene , metallurgy
α‐Crystallin was found to exhibit a time‐dependent uptake of the hydrophobic probe, 1‐anilinonaph‐thalene‐8‐sulfonic acid (ANS), similar to that typically observed with lipid membranes. Analysis of the interaction of ANS with α‐crystallin revealed two types of interactive processes, partitioning and binding. The predominant process involved partitioning, with a coefficient of 300 M −1 . The binding component had the following characteristics: 1 binding site/24 subunits and a K d of about 9 μM. The binding was unaffected by the number of subunits used in the assembly of the α‐aggregate, since both the α m ‐ and α c ‐forms had similar binding characteristics. No discernible differences were observed in the binding of ANS to homopolymers of αA and αB subunits, suggesting that the hydrophobic sites to which ANS bound were similar in both the A and B subunits. The majority of the fluorescence was lost when the protein was incubated in 3 M urea, a concentration of denaturant where the protein is still intact, suggesting that the ANS binding sites are located near the surface of the protein. The decrease was attributed to a decrease in the quantum yield of the bound dye.