The protein monellin, derived from these berries, is at least 2500 times as sweet as sucrose and causes sour substances to taste sweet.
Monellin composed of two subunits, one being 45 residues (A chain) and the other 50 residues (B chain). X-0ray and NMR methods indicate the structure of monellin has a five-strand antiparallel beta-sheet and a 15 residue alpha-helix.
Monellin undergoes irreversible thermal unfolding at pH 2.5 and 85 °C. leading to an unfolded-like conformation.
It was not commercially viable in its natural form since the protein is unstable, even within a few days at 20 °C and is lost in heating.
Monellin was first purified in 1972. It is heterodimer consisting of 44 amino acid residue A chain and a 50 amino acid residue B chain, held together by non-covalent interactions.
The overall molecular mass is 11kDa and the protein displays a pI value of 9.0 – 9.4.
The protein of monellin
