Binding site conformation dictates the color of the dye stains-all. A study of the binding of this dye to the eye lens proteins crystallins.
The interaction of the cationic carbocyanine dye Stains-all (1-ethyl-2-[3-(1-ethyl-naphthol[1,2-d]thiazolin-2-ylidene)-2- methylpropenyl]naphthol[1,2-d]thiazolium bromide) with the eye lens proteins crystallins has been studied. alpha- and gamma-crystallins do not bind the dye, while beta- and delta-crystallins do, consistent with the fact that the latter two proteins bind the calcium ion. beta-Crystallin resembles parvalbumin in that it induces only the J-band of the bound dye. delta-crystallin, on the other hand, induces only the gamma-band. Analysis of the metachromasia induced in the dye by these and other proteins suggests that Stains-all is responsive to the conformational status of the region to which it binds in a protein. The J-band of the dye is activated when it binds to a globular domain, and the gamma-band is activated when it binds to a helical stretch of the protein.
Sharma
Y
Y
Centre for Cellular and Molecular Biology, Hyderabad, India.
Rao
C M
CM
Rao
S C
SC
Krishna
A G
AG
Somasundaram
T
T
Balasubramanian
D
D
D000818:Animals; D001665:Binding Sites; D002122:Calcium Chloride / Q000494:pharmacology; D002232:Carbocyanines / Q000378:metabolism*; D002942:Circular Dichroism; D003459:Crystallins / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011804:Quinolines / Q000378:metabolism*; D051381:Rats; D013053:Spectrophotometry; D013194:Staining and Labeling; D013329:Structure-Activity Relationship
D002232:Carbocyanines; D003459:Crystallins; D011804:Quinolines; C012040:stains-all; D002122:Calcium Chloride