Charged groups vinegar-like

Drugs, containing charge, pair with oppositely charged vinegar-like groups of the elastic model protein. 

Figure 2.1. The phase transition of oil-like groups separating from water produces motion. A A protein is described as a polypeptide chain molecule with different side chains, R-groups. B The side chains delineated simply as oil-like and vinegar-like (e.g., charged), are distributed along the chain. C The separation of oil-like groups from vinegar-like groups and the association of oil-like groups to form oil-like...

Moving the T,-divide by Ion Pairing with Oppositely Charged Vinegar-like R-groups... 

Adding add (proton, H ) converts the negatively charged vinegar-like R-group (-CH2-... 

Considering reaction (ii) of Figure 5.16, addition of base (hydroxyl ion, OH") converts the positively charged vinegar-like R-group (-CH2-CH2-CH2-CH2-NH3 ) of the lysine residue to -CH2-CH2-CH2-CH2-NH2, that is, -CH2-CH2-CH2-CH2-NH3 + OH" -CH2-CH2-CH2-CH2-NH2 + H2O. 

The vinegar-like side chains can exist in either of two different states, for example, the car-boxyl/carboxylate, COOH/COO, chemical couple and the amino/ammonium, -NH2/NH3, chemical couple. As demonstrated below, the uncharged state of the couple favors association of oil-like domains, whereas the charged state of the couple disrupts association of oillike domains by having destroyed the special hydration of oil-like groups in the process of achieving its own hydration. 

Here we note more general terms polar for vinegar-like or for charged or ionized and apolar for oil-like or hydrophobic, but recognize that there exist a continuum of groups from polar to apolar. 

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