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When a proton attacks cellobiose in the gas phase: ab initio molecular dynamics simulations
Madeleine Pincu1, Brina Brauer, R Benny Gerber
1Department of Chemistry, University of California, Irvine, California 92697-2025, USA. bgerber@uci.edu.
Physical Chemistry Chemical Physics : PCCP
|August 13, 2013
Summary
Protonating cellobiose (CB) initiates rapid reactions like bond breaking and water formation. The cis form of protonated CB is more stable than the trans form in a vacuum.
Area of Science:
- Computational Chemistry
- Biochemistry
- Molecular Dynamics
Background:
- Cellobiose (CB) is a glucose disaccharide crucial in biological and chemical processes.
- Understanding proton interactions with cellobiose is key to elucidating its reactivity.
- Previous studies lack detailed insights into the dynamic reaction pathways of protonated cellobiose.
Purpose of the Study:
- To investigate the reaction pathways of a proton interacting with cis and trans cellobiose (CB).
- To explore the transient chemical events occurring in protonated cellobiose (H(+)CB) at elevated temperatures.
- To determine the relative energetic stability of cis and trans protonated cellobiose in a vacuum.
Main Methods:
- Ab Initio Molecular Dynamics (AIMD) simulations were employed.
- Simulations started with protons placed near high-affinity sites on cis and trans cellobiose.
- System dynamics were analyzed near and above 300 K over a 10 ps timescale.
Main Results:
- Protonated cellobiose (H(+)CB) exhibited rapid, transient reactions within 10 ps.
- Observed reactions included charge transfer, water formation/dehydration, ring and glycosidic bond breaking, mutarotation, and ring puckering.
- cis H(+)CB was found to be energetically more stable than trans H(+)CB in a vacuum, with a larger energy gap than neutral CB.
Conclusions:
- Protonation dramatically alters cellobiose's reactivity, inducing diverse chemical transformations on short timescales.
- The cis configuration of protonated cellobiose offers significant energetic stabilization compared to the trans form.
- These findings provide critical molecular-level insights into the behavior of protonated disaccharides.
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