Induced optical activity of acridine orange bound to poly-S-carboxymethyl-L-cysteine

✍ Scribed by Shoiohi Ikkda; Toyoko Imae

• Publisher: Wiley (John Wiley & Sons)
• Year: 1971
• Tongue: English
• Weight: 776 KB
• Volume: 10
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360101002

✦ Synopsis

The absorption and rotatory properties of acridine orange-poly-Scarboxymethy1-Lcysteine system in water and in 0.2 M NaCl have been measured at different pH and polymer-to-dye mixing ratios. The absorption spectra indicate that the dyes are bound to the polymer in dimeric or highly aggregated forms. At neutral pH where the polymer is randomly coiled, no optical activity is induced on the absorption bands of bound acridine orange. At acid pH where the polymer has the @-conformation, a pair of positive and negative circular dichroic bands occur at each of the absorption bands, centered around 4.58 and 261 mp. The signs of thwe bands are opposite to those found for a-heli-(:a1 poly-bglutamic acid. A model for the binding of dye to the@-form polymer is presented, in which dimeric dyes are attached to ionized carboxyl groups and stack one another to form linear arrays on both sides of an extended polypeptide chain. The observed circular dichroism spectra ran be explained by the Tinoco's exciton mechanism, based on this model. Low molecular weight poly-Scarboxymethyl-Lcysteine induces quite R different c i r d a r dirhroism 011 boiind arridine orange.