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Low-barrier hydrogen bonds and enzymic catalysis
1Institute for Enzyme Research, University of Wisconsin, Madison 53705.
Science (New York, N.Y.)
|June 24, 1994
Summary
Enzymes catalyze reactions by forming strong, low-barrier hydrogen bonds in transition states. This mechanism, crucial for difficult reactions like carboxylate enolization, stabilizes intermediates by matching pKa values.
Area of Science:
- Biochemistry
- Enzymology
- Chemical Catalysis
Background:
- Enzymic catalysis often involves stabilizing transition states or enzyme-intermediate complexes.
- Hydrogen bonds play a critical role in molecular interactions and reaction mechanisms.
Purpose of the Study:
- To explore the role of short, strong, low-barrier hydrogen bonds in enzymic catalysis.
- To investigate how matching pKa values in transition states contribute to catalytic efficiency.
Main Methods:
- Analysis of hydrogen bond characteristics (length < 2.5 Å) in enzyme active sites.
- Evaluation of energy contributions (10-20 kcal/mol) from low-barrier hydrogen bonds.
- Examination of pKa matching between donor and acceptor atoms in enzyme-substrate complexes and transition states.
Main Results:
- Low-barrier hydrogen bonds in transition states can provide significant catalytic energy.
- These bonds facilitate challenging reactions, such as the enolization of carboxylate groups.
- Matching of pKa values is essential for the formation of strong, low-barrier hydrogen bonds.
Conclusions:
- The formation of low-barrier hydrogen bonds is a key strategy in enzymic catalysis.
- Enzymes utilize dynamic pKa matching in transition states to enhance catalytic power.
- This principle is applicable to various enzymatic reactions facilitating difficult chemical transformations.