Characterization of the restricted rotation of the dimethyl groups in chemically N -terminal 13C-labeled antifreeze glycoproteins: A temperature-dependent study in water to ice through the supercooled state

Viswanathan V Krishnan, Edmond Y Lau, Nelly M. Tsvetkova, Robert E. Feeney, William H. Fink, Yin Yeh

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Site-specific chemical modification, especially with isotopically enriched groups, allows one to study the structure and dynamics of proteins for which uniform enrichment is difficult. When the N -terminal alanine in antifreeze glycoprotein (AFGP) is replaced with an N,N -dimethyl alanine the methyl groups show signatures of slow rotation about the C-N bond. In order to separate the local dynamics of the N -terminus from the overall protein dynamics, we present a complete characterization of this dynamics. Temperature-dependent nuclear magnetic-resonance experiments from room temperature to subzero temperatures, including the supercooled state and in the presence of ice, are presented. Quantum chemical calculations are also performed on a localized N -terminus of the AFGP. Our results show that in the solution state at room temperature and in the super cooled regime, the dimethyl groups undergo a slow, restricted rotation with an unequal distribution of population between two major conformations. At lower temperatures in the presence of ice, the dynamics become much more complex due to freezing out of several conformational states. Based on these results, we conclude that the segmental dynamics of the N -terminus are local to the first residue and do not affect the overall dynamics of the protein.

Original languageEnglish (US)
Article number044702
JournalJournal of Chemical Physics
Volume123
Issue number4
DOIs
StatePublished - 2005
Externally publishedYes

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antifreezes
Antifreeze Proteins
Ice
ice
Water
water
Temperature
alanine
temperature
proteins
Alanine
subzero temperature
Proteins
Chemical modification
room temperature
Freezing
freezing
Conformations
signatures
Nuclear magnetic resonance

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

@article{187266b2503e46c092dacdf7f3ada77f,
title = "Characterization of the restricted rotation of the dimethyl groups in chemically N -terminal 13C-labeled antifreeze glycoproteins: A temperature-dependent study in water to ice through the supercooled state",
abstract = "Site-specific chemical modification, especially with isotopically enriched groups, allows one to study the structure and dynamics of proteins for which uniform enrichment is difficult. When the N -terminal alanine in antifreeze glycoprotein (AFGP) is replaced with an N,N -dimethyl alanine the methyl groups show signatures of slow rotation about the C-N bond. In order to separate the local dynamics of the N -terminus from the overall protein dynamics, we present a complete characterization of this dynamics. Temperature-dependent nuclear magnetic-resonance experiments from room temperature to subzero temperatures, including the supercooled state and in the presence of ice, are presented. Quantum chemical calculations are also performed on a localized N -terminus of the AFGP. Our results show that in the solution state at room temperature and in the super cooled regime, the dimethyl groups undergo a slow, restricted rotation with an unequal distribution of population between two major conformations. At lower temperatures in the presence of ice, the dynamics become much more complex due to freezing out of several conformational states. Based on these results, we conclude that the segmental dynamics of the N -terminus are local to the first residue and do not affect the overall dynamics of the protein.",
author = "Krishnan, {Viswanathan V} and Lau, {Edmond Y} and Tsvetkova, {Nelly M.} and Feeney, {Robert E.} and Fink, {William H.} and Yin Yeh",
year = "2005",
doi = "10.1063/1.1924549",
language = "English (US)",
volume = "123",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
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}

TY - JOUR

T1 - Characterization of the restricted rotation of the dimethyl groups in chemically N -terminal 13C-labeled antifreeze glycoproteins

T2 - A temperature-dependent study in water to ice through the supercooled state

AU - Krishnan, Viswanathan V

AU - Lau, Edmond Y

AU - Tsvetkova, Nelly M.

AU - Feeney, Robert E.

AU - Fink, William H.

AU - Yeh, Yin

PY - 2005

Y1 - 2005

N2 - Site-specific chemical modification, especially with isotopically enriched groups, allows one to study the structure and dynamics of proteins for which uniform enrichment is difficult. When the N -terminal alanine in antifreeze glycoprotein (AFGP) is replaced with an N,N -dimethyl alanine the methyl groups show signatures of slow rotation about the C-N bond. In order to separate the local dynamics of the N -terminus from the overall protein dynamics, we present a complete characterization of this dynamics. Temperature-dependent nuclear magnetic-resonance experiments from room temperature to subzero temperatures, including the supercooled state and in the presence of ice, are presented. Quantum chemical calculations are also performed on a localized N -terminus of the AFGP. Our results show that in the solution state at room temperature and in the super cooled regime, the dimethyl groups undergo a slow, restricted rotation with an unequal distribution of population between two major conformations. At lower temperatures in the presence of ice, the dynamics become much more complex due to freezing out of several conformational states. Based on these results, we conclude that the segmental dynamics of the N -terminus are local to the first residue and do not affect the overall dynamics of the protein.

AB - Site-specific chemical modification, especially with isotopically enriched groups, allows one to study the structure and dynamics of proteins for which uniform enrichment is difficult. When the N -terminal alanine in antifreeze glycoprotein (AFGP) is replaced with an N,N -dimethyl alanine the methyl groups show signatures of slow rotation about the C-N bond. In order to separate the local dynamics of the N -terminus from the overall protein dynamics, we present a complete characterization of this dynamics. Temperature-dependent nuclear magnetic-resonance experiments from room temperature to subzero temperatures, including the supercooled state and in the presence of ice, are presented. Quantum chemical calculations are also performed on a localized N -terminus of the AFGP. Our results show that in the solution state at room temperature and in the super cooled regime, the dimethyl groups undergo a slow, restricted rotation with an unequal distribution of population between two major conformations. At lower temperatures in the presence of ice, the dynamics become much more complex due to freezing out of several conformational states. Based on these results, we conclude that the segmental dynamics of the N -terminus are local to the first residue and do not affect the overall dynamics of the protein.

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