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Importance of Glu53 in the C‐terminal region of brazzein, a sweet‐tasting protein
Author(s) -
Lim JinKyung,
Jang JinChul,
Kong JiNa,
Kim MyungChul,
Kong KwangHoon
Publication year - 2016
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.7501
Subject(s) - sweetness , chemistry , biochemistry , residue (chemistry) , thaumatin , mutagenesis , sweet taste , mutant , taste , food science , gene
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. Mutations of Glu53 substitution to Ala or Asp significantly decreased the sweetness. On the other hand, a Lys mutation resulted in a molecule with sweetness similar to that of des‐ pE1M ‐brazzein. Mutation of Glu53 to Arg resulted in a molecule significantly sweeter than des‐ pE1M ‐brazzein, which agrees with previous findings showing that mutation with positively charged residues results in a sweeter protein. CONCLUSION Our results suggest that the residue at position 53 is crucial for the sweetness of brazzein, which may be interacting with the sweet‐taste receptor. © 2015 Society of Chemical Industry