Hydrophobicity of peptides and proteins

Amino acids have a range of physical properties, each having a greater or lesser degree of hydrophilic or hydrophobic nature. Naturally, if amino acids are spatially arranged in a molecule so that distinct hydrophobic and hydrophilic regions appear, then the polypeptide or 

Hgure 11.1 (a) The a-helix forms because —NH and —C=0 groups interact through hydrogen bonding pulling the 

Side-chain-side-chain electrostatic interactions 2 kJ mol  

An idea of the overall hydrophobicity of a peptide or protein may be gained from the use of indices of the hydrophobicity of the individual amino acids. Secondary and tertiary stmctures are important in determining the 

If alternating hydrophilic and hydrophobic amino acid sequences in synthetic peptides are at the right distances in space, the molecule coils with the hydrophobic amino acids on the inside of each coil and the hydrophilic ones to the outside. There are still, however, many stmctural mysteries the interior of many protein stmctures with myriads of side-chains, and the way in which metal ions can stabilize three-dimensional stmctures, have been likened to a terra incognita. 

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