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Role of protein surface charge in monellin sweetness.

Xue, Wei-Feng LU ; Szczepankiewicz, Olga LU ; Thulin, Eva LU ; Linse, Sara LU and Carey, Jannette LU (2009) In Biochimica et Biophysica Acta - Proteins and Proteomics2002-01-01+01:00 1794(3). p.410-420
Abstract
A small number of proteins have the unusual property of tasting intensely sweet. Despite many studies aimed at identifying their sweet taste determinants, the molecular basis of protein sweetness is not fully understood. Recent mutational studies of monellin have implicated positively charged residues in sweetness. In the present work, the effect of overall net charge was investigated using the complementary approach of negative charge alterations. Multiple substitutions of Asp/Asn and Glu/Gln residues radically altered the surface charge of single-chain monellin by removing six negative charges or adding four negative charges. Biophysical characterization using circular dichroism, fluorescence, and two-dimensional NMR demonstrates that... (More)
A small number of proteins have the unusual property of tasting intensely sweet. Despite many studies aimed at identifying their sweet taste determinants, the molecular basis of protein sweetness is not fully understood. Recent mutational studies of monellin have implicated positively charged residues in sweetness. In the present work, the effect of overall net charge was investigated using the complementary approach of negative charge alterations. Multiple substitutions of Asp/Asn and Glu/Gln residues radically altered the surface charge of single-chain monellin by removing six negative charges or adding four negative charges. Biophysical characterization using circular dichroism, fluorescence, and two-dimensional NMR demonstrates that the native fold of monellin is preserved in the variant proteins under physiological solution conditions although their stability toward chemical denaturation is altered. A human taste test was employed to determine the sweetness detection threshold of the variants. Removal of negative charges preserves monellin sweetness, whereas added negative charge has a large negative impact on sweetness. Meta-analysis of published charge variants of monellin and other sweet proteins reveals a general trend toward increasing sweetness with increasing positive net charge. Structural mapping of monellin variants identifies a hydrophobic surface predicted to face the receptor where introduced positive or negative charge reduces sweetness, and a polar surface where charges modulate long-range electrostatic complementarity. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochimica et Biophysica Acta - Proteins and Proteomics2002-01-01+01:00
volume
1794
issue
3
pages
410 - 420
publisher
Elsevier
external identifiers
  • wos:000263776300003
  • pmid:19100868
  • scopus:59349113561
ISSN
1570-9639
DOI
10.1016/j.bbapap.2008.11.008
language
English
LU publication?
yes
id
a818b95a-bbf2-409c-878f-aff0abaa6357 (old id 1276007)
date added to LUP
2009-01-29 15:55:16
date last changed
2017-12-10 04:04:55
@article{a818b95a-bbf2-409c-878f-aff0abaa6357,
  abstract     = {A small number of proteins have the unusual property of tasting intensely sweet. Despite many studies aimed at identifying their sweet taste determinants, the molecular basis of protein sweetness is not fully understood. Recent mutational studies of monellin have implicated positively charged residues in sweetness. In the present work, the effect of overall net charge was investigated using the complementary approach of negative charge alterations. Multiple substitutions of Asp/Asn and Glu/Gln residues radically altered the surface charge of single-chain monellin by removing six negative charges or adding four negative charges. Biophysical characterization using circular dichroism, fluorescence, and two-dimensional NMR demonstrates that the native fold of monellin is preserved in the variant proteins under physiological solution conditions although their stability toward chemical denaturation is altered. A human taste test was employed to determine the sweetness detection threshold of the variants. Removal of negative charges preserves monellin sweetness, whereas added negative charge has a large negative impact on sweetness. Meta-analysis of published charge variants of monellin and other sweet proteins reveals a general trend toward increasing sweetness with increasing positive net charge. Structural mapping of monellin variants identifies a hydrophobic surface predicted to face the receptor where introduced positive or negative charge reduces sweetness, and a polar surface where charges modulate long-range electrostatic complementarity.},
  author       = {Xue, Wei-Feng and Szczepankiewicz, Olga and Thulin, Eva and Linse, Sara and Carey, Jannette},
  issn         = {1570-9639},
  language     = {eng},
  number       = {3},
  pages        = {410--420},
  publisher    = {Elsevier},
  series       = {Biochimica et Biophysica Acta - Proteins and Proteomics2002-01-01+01:00},
  title        = {Role of protein surface charge in monellin sweetness.},
  url          = {http://dx.doi.org/10.1016/j.bbapap.2008.11.008},
  volume       = {1794},
  year         = {2009},
}