Salt linkages

Nucleoproieins. The prosthetic group of the nucleoproteins is nucleic acid, often linked through salt linkages with protamines or histones. The nucleoproteins are present in the nuclei of all cells. Chromasomes are largely nucleoproteins and some plant viruses and bacteriophages have been shown to be pure nucleoproteins. See also histones. 

The 1 2 metal complex dyes are dyed either at neutral pH or with ammonium acetate, and the exhaustion achieved by the effect of van der Waals forces. The pH is then aUowed to go slightly acidic to form salt linkages between the dye anion and the protonated primary amine groups in the wool (NH3 ). AU the dyes have similar dyeing properties and the conditions of appHcation do not damage the wool. 

Penetration of dimethyl phosphite into the fibre, accompanied by decomposition of salt linkages and elimination of structural water in a multi-step hydration process. New salt linkages are formed between cationic groups in wool keratin and anionic dimethyl phosphite. 

On the basis of the interaction of metal ions and AV-pH and AV-log C plots (41, 43), we propose ionic structures for dioleoyl, egg, and di-palmitoyl lecithin monolayers represented in Figure 1. Schematically shown in Figure 1A is the internal salt linkage between the phosphate and trimethylammonium groups in dioleoyl lecithin, preventing the inter-... 

A Dioleoyl lecithin shows internal salt linkage between phosphate and trimethyl-ammonium groups. Broken lines in egg lecithin diagram represents weak interactions of phosphate with Ca2+ and trimethylammonium group. Solid line between Ca + and phosphate group in dipalmitoyl lecithin diagram represents strong interaction... 

B Egg lecithin-cholesterol monolayers. Increased spacing between phosphate groups results in strong internal salt linkage preventing binding of Ca2+... 

The interaction of metal ions with lecithin monolayers, as measured by the increase in surface potential, decreases with increasing unsaturation of fatty acyl chains. The phosphate and trimethylammonium groups of a lecithin molecule form an internal salt linkage which dissociates upon... 

Attraction between Charged Groups (Salt Linkages)... 

Acid milling dyes are intermediate in behavior, being applied with acetic or formic acid in the presence of sodium sulfate. A disadvantage or acid dyes is that I heir wetfastness depends on the Formation and maintenance or a salt linkage between the charged wool and dye. This requires an acidic inlemal pH to be maintained in the wool. 

An internal sah is a compound in which the acidic or basic groups that react to produce the salt linkage (which may or may not entail the formation of water) are in the same molecule. This particular salt linkage may consist of a polar or a nonpolar bond. 

The general wetfastness properties of acid dyes are normally enhanced in comparison to those of the disperse dyes due to the fact that the hair protein forms additional salt linkages with the anionic dyes. Moreover, the lightfastness is in most cases better than with disperse dyes. The application technique and killing pretreatments for acid dyes are similar to those for disperse dyes. 

Basic (cationic) dyes. Basic dyes are water-soluble and produce colored cations in solution. They are mostly amino and substituted amino compounds soluble in acid and made insoluble by the solution being made basic. They become attached to the fibers by formation of salt linkages (ionic bonds) with anionic groups in the fiber. They are used to dye paper, polyacrylonitrile, modified nylons, and modified polyesters. In solvents other than water, they form writing and printing inks. The principal chemical classes are triaryl methane or xanthenes. Basic brown 1 is an example of a cationic dye that is readily protonated under the pH 2 to 5 conditions of dyeing [5]. 

Owing to the presence of many amine, carboxylic acid, amide, and other polar groups, wool and silk are hydrophilic in nature, wetted by water, and are dyed with either acid or basic dyes through the formation of ionic bonds (salt linkages). They may also be dyed with reactive dyes that form covalent bonds with available amino groups. 

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