Lernmaterialien für Biomedizinische Grenzflächen an der ETHZ - ETH Zurich

1) long-ranged, electrostatic

2) van der waals

• water in hydration shell tends to be oriented
  • -> ion hydration thus decreases the entropy of the solvent

• orientation of solvent molecules due to the strong orientation dependence of their ion-(free rotating) dipole interaction

• number of bound water molecules given by hydration number

hydrogen bonds can occur intermolecularly and intramolecularly

tetrahedral arrangement between water molecules remain

offering of interaction possibilities with water molecules:

• H-bond accepting or donating groups
  • O in carbonyl groups C=O; carboxylates (COO-); sulfonates (SO3-)
  • H in amine -NH2 groups or in hydroxyl -OH groups
• charged/zwitterionic surfaces
  • charge-dipole, (fixed dipole)-dipole
  • polyelectrolytes / polysaccharides
  • soluble proteins
  • nucleic acids (DNA, RNA)

§ The principle interactions between biological materials
(including cells) happen on the molecular level
§ Biological (macro)molecules are complicated structures
§ They cannot be described exactly by simple properties
§ To understand them, we need to know the behavior of their elemental building blocks

§ Importantly, everything happens in/with water (solvent)