Structure of LacY with an α-substituted galactoside: Connecting the binding site to the protonation site
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- Hemant Kumar
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158;
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- Janet S. Finer-Moore
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158;
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- H. Ronald Kaback
- Department of Physiology and Department of Microbiology, Immunology, and Molecular Genetics, and Molecular Biology Institute, University of California, Los Angeles, CA 90095
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- Robert M. Stroud
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158;
書誌事項
- 公開日
- 2015-07-08
- 権利情報
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- http://www.pnas.org/site/misc/userlicense.xhtml
- DOI
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- 10.1073/pnas.1509854112
- 公開者
- Proceedings of the National Academy of Sciences
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説明
<jats:title>Significance</jats:title> <jats:p> Substituted <jats:sc>d</jats:sc> -galactopyranosides, particularly those in the α configuration and/or with hydrophobic constituents at the anomeric position, bind to LacY with higher affinity than the physiological substrate lactose that has a β configuration. The structure of a conformationally restricted LacY mutant with bound <jats:italic>p</jats:italic> -nitrophenyl-α- <jats:sc>d</jats:sc> -galactopyranoside (α-NPG), a high-affinity lactose analog, is described. Higher affinity, gained by nonspecific hydrophobic interaction of the nitrophenyl group, shows identical interaction at the key galactosyl moiety as in thio-digalactoside and so validates the highly specific, oriented set of hydrogen bonds with the key galactosyl moiety of substrates. Confirmation of galactose-specific binding interactions delineates a directional hydrogen-bonding network that couples the binding site to sites that are sensitive to protonation in the mechanism. </jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 112 (29), 9004-9009, 2015-07-08
Proceedings of the National Academy of Sciences