Role of protein surface charge in monellin sweetness.

摘要: A small number of proteins have the unusual property tasting intensely sweet. Despite many studies aimed at identifying their sweet taste determinants, molecular basis protein sweetness is not fully understood. Recent mutational monellin implicated positively charged residues in sweetness. In present work, effect overall net charge was investigated using complementary approach negative alterations. Multiple substitutions Asp/Asn and Glu/Gln radically altered surface single-chain by removing six charges or adding four charges. Biophysical characterization circular dichroism, fluorescence, two-dimensional NMR demonstrates that native fold preserved variant under physiological solution conditions although stability toward chemical denaturation altered. human test employed to determine detection threshold variants. Removal preserves sweetness, whereas added has a large impact on Meta-analysis published variants other reveals general trend increasing with positive charge. Structural mapping identifies hydrophobic predicted face receptor where introduced reduces polar modulate long-range electrostatic complementarity.