Importance of Glu53 in the C-terminal region of brazzein, a sweet-tasting protein.

Background: The sweetness of brazzein, one of the known sweet proteins, is dependent on charges and/or structures of its specific amino acid side chains. As the residues in the C-terminus of brazzein are known to play a critical role in sweetness, the currently unknown function of Glu53 requires further study.

Results: To identify important residues responsible for the sweetness of the protein brazzein, four mutants of the Glu53 residue in the C-terminal region of des-pE1M-brazzein, which lacks the N-terminal pyroglutamate, were constructed using site-directed mutagenesis.