Biomaterial Database

Multiple mutations of the critical amino acid residues for the sweetness of the sweet-tasting protein, brazzein. 2013

Joo-Won Lee, and Ji-Eun Cha, and Hyun-Joo Jo, and Kwang-Hoon Kong

Biomolecular Chemistry Laboratory, Department of Chemistry, College of Natural Sciences, Chung-Ang University, 221, Huksuk-Dong, Dongjak-Ku, Seoul 156-756, Republic of Korea.

We have previously identified critical residues important for sweetness of the sweet protein brazzein by site-directed mutagenesis (Yoon, Kong, Jo, & Kong, 2011). In order to elucidate the interaction mechanisms of brazzein with the sweet taste receptor, we made multiple mutations of three residues (His31 in loop 30-33, Glu36 in β-strand III, and Glu41 in loop 40-43). We found that all double mutations (H31R/E36D, H31R/E41A and E36D/E41A) made the molecules sweeter than des-pE1M-brazzein and three single mutants. Moreover, the triple mutation (H31R/E36D/E41A) made the molecule significantly sweeter than three double mutants. These results strongly support the hypothesis that brazzein binds to the multisite surface of the sweet taste receptor. Our findings also suggest that mutations reducing the overall negative charge and/or increasing the positive charge favour sweet-tasting protein potency.

UI	MeSH Term	Description	Entries
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010940	Plant Proteins	Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which PLANT PROTEINS, DIETARY is available.	Plant Protein,Protein, Plant,Proteins, Plant
D013549	Sweetening Agents	Substances that sweeten food, beverages, medications, etc., such as sugar, saccharine or other low-calorie synthetic products. (From Random House Unabridged Dictionary, 2d ed)	Artificial Sweeteners,Sugar Substitutes,Sweeteners,Agent, Sweetening,Agents, Sweetening,Artificial Sweetener,Substitute, Sugar,Substitutes, Sugar,Sugar Substitute,Sweetener,Sweetener, Artificial,Sweeteners, Artificial,Sweetening Agent
D013649	Taste	The ability to detect chemicals through gustatory receptors in the mouth, including those on the TONGUE; the PALATE; the PHARYNX; and the EPIGLOTTIS.	Gustation,Taste Sense,Gustations,Sense, Taste,Senses, Taste,Taste Senses,Tastes
D020816	Amino Acid Motifs	Three-dimensional protein structural elements that are composed of a combination of secondary structures. They include HELIX-LOOP-HELIX MOTIFS and ZINC FINGERS. Motifs are typically the most conserved regions of PROTEIN DOMAINS and are critical for domain function. However, the same motif may occur in proteins or enzymes with different functions.	AA Motifs,Motifs, Amino Acid,Protein Motifs,Protein Structure, Supersecondary,Supersecondary Protein Structure,AA Motif,Amino Acid Motif,Motif, AA,Motif, Amino Acid,Motif, Protein,Motifs, AA,Motifs, Protein,Protein Motif,Protein Structures, Supersecondary,Supersecondary Protein Structures