Molecular recognition. 15. Molecular recognition and stereoselectivity: geometrical requirements for the multiple hydrogen-bonding interaction of diols with a multidentate polyhydroxy macrocycle

1991 ◽  
Vol 113 (4) ◽  
pp. 1349-1354 ◽  
Author(s):  
Yasuaki Kikuchi ◽  
Yasushi Kato ◽  
Yasutaka Tanaka ◽  
Hiroo Toi ◽  
Yasuhiro Aoyama
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Recognition ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction ◽  
Multiple Hydrogen Bonding

Radical Enzymes Control the Chemistry of Their Highly Reactive Intermediates Using the Quantum Coulombic Effect

2020 ◽  
Author(s):  
Hossein Khalilian ◽  
Gino A. DiLabio
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Orbital ◽  
Reactive Intermediates ◽  
Hydrogen Bonding Interaction ◽  
Orbital Ordering ◽  
Dynamic Nature ◽  
Radical Intermediate ◽  
Highest Occupied Molecular Orbital ◽  
Bonding Interaction ◽  
Close Proximity

Here, we report an exquisite strategy that the B12 enzymes exploit to manipulate the reactivity of their radical intermediate (Adenosyl radical). Based on the quantum-mechanic calculations, these enzymes utilize a little known long-ranged through space quantum Coulombic effect (QCE). The QCE causes the radical to acquire an electronic structure that contradicts the Aufbau Principle: The singly-occupied molecular orbital (SOMO) is no longer the highest-occupied molecular orbital (HOMO) and the radical is unable to react with neighbouring substrates. The dynamic nature of the enzyme and its structure is expected to be such that the reactivity of the radical is not restored until it is moved into close proximity of the target substrate. We found that the hydrogen bonding interaction between the nearby conserved glutamate residue and the ribose ring of Adenosyl radical plays a crucial role in manipulating the orbital ordering

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