Hindered Rotations of Protein Asparagine/Glutamine Side-Chain NH 2 Groups: Impact of Hydrogen Bonding with DNA

Hindered rotation about an sp C-N bond is known to occur in arginine (Arg), asparagine (Asn), and glutamine (Gln) side chains of proteins. However, very little is known about the rotational dynamics of Asn and Gln side-chain NH groups. Here, using a unique NMR method, we quantitatively characterized...

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Bibliographic Details
Published in:The journal of physical chemistry letters 2021-11, Vol.12 (46), p.11378-11382
Main Authors: Wang, Xi, Yu, Binhan, Iwahara, Junji
Format: Article
Language:English
Subjects:
Asparagine - chemistry
DNA - chemistry
Glutamine - chemistry
Hydrogen Bonding
Kinetics
Nuclear Magnetic Resonance, Biomolecular
Temperature
Thermodynamics
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Summary:Hindered rotation about an sp C-N bond is known to occur in arginine (Arg), asparagine (Asn), and glutamine (Gln) side chains of proteins. However, very little is known about the rotational dynamics of Asn and Gln side-chain NH groups. Here, using a unique NMR method, we quantitatively characterized the hindered rotations of protein Asn/Gln side-chain NH groups. This NMR method yields simple NH -selective spectra that allow for an accurate determination of the kinetic rate constants for the hindered rotations. Through the NMR measurements at different temperatures, we investigated the energy barriers that restrict the C-N bond rotations of protein side-chain NH groups. Through a comparison of the kinetic data for the free and DNA-bound states of the Antp homeodomain, we also examined the impact of hydrogen bonding on the hindered rotations of the side-chain NH groups. Our data suggest that the hydrogen bonding increases the energy barriers by 1-6 kJ/mol.
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.1c03467