title: Design of sweet protein based sweeteners: hints from structure-function relationships.
abstract: Sweet proteins represent a class of natural molecules, which are extremely interesting regarding their potential use as safe low-calories sweeteners for individuals who need to control sugar intake, such as obese or diabetic subjects. Punctual mutations of amino acid residues of MNEI, a single chain derivative of the natural sweet protein monellin, allow the modulation of its taste. In this study we present a structural and functional comparison between MNEI and a sweeter mutant Y65R, containing an extra positive charge on the protein surface, in conditions mimicking those of typical beverages. Y65R exhibits superior sweetness in all the experimental conditions tested, has a better solubility at mild acidic pH and preserves a significant thermal stability in a wide range of pH conditions, although slightly lower than MNEI. Our findings confirm the advantages of structure-guided protein engineering to design improved low-calorie sweeteners and excipients for food and pharmaceutical preparations.
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy.
authors.forename: Michele Fortunato
authors.initials: MF
authors.lastname: Rega
authors.affiliation: Food Science and Agricultural Department, University of Naples - Federico II, Italy; Centre for Food Innovation and Development, University of Naples, Portici, Italy.
authors.forename: Rossella
authors.initials: R
authors.lastname: Di Monaco
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Leone
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Donnarumma
authors.affiliation: Department of Science and Technology, University of Sannio, 82100 Benevento, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Spadaccini
authors.affiliation: Food Science and Agricultural Department, University of Naples - Federico II, Italy; Centre for Food Innovation and Development, University of Naples, Portici, Italy.
authors.forename: Silvana
authors.initials: S
authors.lastname: Cavella
authors.affiliation: Department of Chemical Sciences, University of Naples Federico II, via Cintia, 80126 Naples, Italy. Electronic address: delia.picone@unina.it.
authors.forename: Delia
authors.initials: D
authors.lastname: Picone
mesh_terms: D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D050505:Mutant Proteins / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry*; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013549:Sweetening Agents / Q000737:chemistry*; D013649:Taste
chemical_list: D050505:Mutant Proteins; D010940:Plant Proteins; D013549:Sweetening Agents; C002541:monellin protein, Dioscoreophyllum cumminsii
keywords: MNEI; Monellin; Protein sweeteners; Single-chain monellin; Sweet proteins