Could a polyAla sequence form a beta sheet Why or why notSol

Could a poly-Ala sequence form a beta sheet? Why or why not?

Solution

Protein secondary structures are formed due to hydrogen interactions between amino acids present in linear polypeptide. Alfa helix and beta sheets are the typical secondary structures. Alfa helix formed due to intra chain hydrogen interactions and beta chains formed due to inter chain hydrogen interactions. In both cases hydrogen interactions play crucial role. The hydrogen interactions formed between partial charged atoms. Partial charged atoms exists due to dipole moment. Dipole moment observed in molecule with different electro negative atoms. Here alanine contain, a non ionic, hydrophobic side chain, that is Alanine. So it cannot form hydrogen interactions. So cannot form beta sheets