polyLalanine

Poly-L-alanine is a synthetic homopolymer consisting of L-alanine residues linked by peptide bonds. The repeating unit arises from the alanine side chain, a methyl group, giving the polymer a predominantly hydrophobic character compared with polypeptides that bear charged side chains. The polymer can be prepared in a range of lengths, from short oligomers to higher molecular weights, and its properties depend on chain length and stereochemistry.

It is commonly synthesized by polymerizing N-carboxyanhydride derivatives of L-alanine or by methods that protect and then condense alanine derivatives. The L configuration promotes a tendency to adopt alpha-helix–like conformations in suitable environments. In solution, poly-L-alanine exhibits helix-coil equilibria, with longer chains favoring more ordered alpha-helical structures. In the solid state, it can crystallize into alpha-helical crystals, reflecting its intrinsic helix propensity.

The polymer is generally biodegradable and biocompatible, with physical states ranging from viscous solutions to solid films or fibers depending on molecular weight and processing. Its well-defined secondary-structure tendencies make poly-L-alanine a useful model system for studying protein folding and helix stabilization, and it has been explored as a component in biomaterials research. Applications include biodegradable materials, films, hydrogels, and drug-delivery platforms, often in blends with other biopolymers or with functional side groups to tailor properties.

Note: Poly-L-alanine is distinct from pathological polyalanine repeats observed in some human proteins; the name refers to synthetic polymers composed of L-alanine units.