Amino-acid homopolymers occurring in nature

Microorganisms are capable of producing a wide variety of biopolymers.

Homopolymer peptides, which are made up of only a single type of amino acid, are far less ubiquitous.

The only two amino-acid homopolymers known to occur in nature are presented in this volume.Poly-epsilon-L-lysine is a polycationic peptide and exhibits antimicrobial activity against a wide spectrum of microorganisms.

It is both safe and biodegradable and is therefore used as a food preservative in several countries.

In addition, there has been great interest in medical and other applications of poly-lysine and its derivatives.In contrast, poly-gamma-glutamic acid is an unusual anionic polypeptide.

It is also water soluble, biodegradable, edible, non-toxic and non-immunogenic and can be chemically modified to introduce various drugs.

These features are very useful for pharmaceutical and biomedical applications.

Poly-glutamic acid is also a highly attractive as a food ingredient.