Design of sweet protein based sweeteners: hints from structure-function relationships.

Area of Science:

• Biochemistry
• Food Science
• Protein Engineering

Background:

• Sweet proteins are natural, low-calorie sweeteners with potential for sugar control in obese and diabetic individuals.
• Modifications to the MNEI protein, a derivative of monellin, can alter its taste properties.
• Protein engineering offers a pathway to develop improved sweetener molecules.

Purpose of the Study:

• To structurally and functionally compare the natural sweet protein MNEI with a hyper-sweet mutant Y65R.
• To evaluate the performance of MNEI and Y65R under conditions simulating typical beverage consumption.
• To assess the potential of engineered sweet proteins as food and pharmaceutical excipients.

Main Methods:

• Site-directed mutagenesis was used to create the Y65R mutant of MNEI.
• Comparative analysis of sweetness, solubility, and thermal stability was performed.
• Experiments were conducted under various pH and temperature conditions mimicking beverage environments.

Main Results:

• The Y65R mutant demonstrated superior sweetness compared to MNEI across all tested conditions.
• Y65R exhibited improved solubility at mildly acidic pH.
• Both proteins maintained significant thermal stability, with Y65R showing slightly lower stability than MNEI.

Conclusions:

• Structure-guided protein engineering is effective for designing enhanced low-calorie sweeteners.
• The Y65R mutant shows significant potential as a safe, low-calorie sweetener and excipient.
• Further development of engineered sweet proteins could benefit food and pharmaceutical industries.