Binding of ampholine to transfer RNA.

The melting temperature of isoaccepting tRNAfMet is affected by Ampholine. The plot of Tm versus the logarithm of Ampholine concentration shows clearly an increasing effect of Ampholine when the pH changes from 7.4 to 4.2. This result is interpreted as binding of Ampholine to the nucleic acid. The effects of Ampholine have been compared with those of soidum, magnesium and tetraethylene pentamine. Ampholine carrier ampholytes at pH 4.2 bind to tRNA with the same affinity as magnesium; at higher pH values they are less active. An hypothesis for the mechanism of action of Ampholine on nucleic acids during isoelectric focusing is proposed.