Polypeptides polar-chain pleated sheet

Fig. 6. The folding of the polypeptide chain in a p-pleated sheet, (a) Hydrogen bonding between two sections of a polypeptide chain forming a p-pleated sheet (b) a side-view of one of the polypeptide chains in a /3-pleated sheet showing the side-chains (R groups) attached to the Ca atoms protruding above and below the sheet (c) because the polypeptide chain has polarity either parallel or antiparallel /3-pleated sheets can form.

To summarize, the complex formation between cationic polypeptides and anionic surfactants is initiated through coulombic interaction and followed by a cooperative binding of successive surfactant ions. The nonpolar tails of clustered surfactant molecules can provide a hydrophobic environment that stabilizes an ordered conformation — a helix or a 8-form, which depends not only on the number of methylene groups of lysine and its homologs but also on the chain length of the surfactants. Excess surfactant molecules may cluster onto the bound surfactant ions in a "double layer" fashion with their polar heads exposed to the aqueous medium and nonpolar tails shielded from the polar environment. For the 8-pleated sheets a bilayer can also be formed between bound surfactant molecules which are sandwiched between two polypeptide chains. 

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