Charge neutralization affinity

Acid milling dyes have medium neutral affinity and dyeing can commence on neutrally charged wool. If excess positive charges exist then rapid absorption and unlevel dyeing result. Usually acetic acid is sufficient to generate the requisite number of sites. 

AEpa denotes the proton affinities which are always negative quantities for neutral molecules and anions. Because of the negative charge, proton affinities of anions are larger in absolute value than those of neutral molecules and hence AEp,. is positive. 

IEs for positive ions always increase with the charge. Electron affinities are the IEs of negative ions and are always less than IEs for neutral atoms. 

Through a combination of site-specific mutations and biophysical measurements, it has recently been demonstrated that carboxylate groups at the surface of the protein, but not directly ligated to the bound Ca ions, have a profound effect on the Ca " " affinity. Neutralization of the surface charges reduces affinity and increases the stability of the protein toward unfolding by urea. ... 

Peptide nucleic acids (PNA Fig. 10) are synthetic polynu-cleobase molecules which bind to DNA and RNA with high affinity and specificity. PNA was constructed with a charge-neutral, achiral, pseudopeptide backbone and is therefore chemically more closely related to peptides than to nucleic acids. Thus, PNAs, because of their backbone properties, show extremely good nucleic acid hybridization properties. In fact, PNA-DNA and PNA-RNA duplexes are, in general, thermally more stable than the corresponding DNA(RNA)-DNA(RNA) duplexes. 

Acid Leveling Dyes. These are molecular dispersions at low temperatures (tme solutions) and are simple molecules. They have low affinity at neutral pH and exhibit ionic attraction at acidic pH when the wool becomes charged. They exhibit good leveling and migration behavior. Their low affinity however also results in low fastness. 

---