Water: Structure, Basic physical properties, Molecular Structure, Polarity, Hydrophobic and Hydrophilic Interactions
Hydrophobic and Hydrophilic Interactions:
The most essential biological function of water is as a solvent. It can dissolve a wide range of essential compounds, from simple salts to tiny molecules like sugars and metabolites to huge molecules like proteins and nucleic acids. Chemical reactions, molecule association and binding, diffusion-driven interactions, and ion conduction are all molecular activities that occur at substantial rates only in solution, emphasising the relevance of water’s solvent qualities.
Water’s differential effect as a solvent – the fact that it dissolves some molecules considerably better than others – is just as essential as its ability to dissolve certain compounds. The solubilities are 50 orders of magnitude higher! Ions and charged amino acids like arginine and aspartic acid are found at the high end of the spectrum. These are hydrophilic solutes (water-loving). Asparagine, the peptide backbone of proteins, the phosphate sugar backbone of nucleic acids, sugars, and lipid head groups are all included in this category of neutral amino acids. Aliphatic amino acids like leucine, aromatic amino acids like phenylalanine, and lipid hydrocarbon ‘tails’ are all on the low solubility end of the spectrum. Hydrophobic solutes are those that repel water. Other solutes, such as nucleic acid bases and the amino acid tryptophan, have a range of solubility and can’t be categorised as either hydrophobic or hydrophilic.