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Published on: July 19, 2019
Magnesium isotope effects in enzymatic phosphorylation.
Anatoly L Buchachenko1, Dmitry A Kouznetsov, Natalia N Breslavskaya
1N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 119991 Moscow, Russia. abuchach@chph.ras.ru
The Journal of Physical Chemistry. B
|February 6, 2008
Summary
Enzymatic adenosine triphosphate (ATP) synthesis is faster with magnetic 25Mg isotopes, revealing a spin-dependent ion-radical mechanism. This magnetic isotope effect (MIE) highlights novel enzyme mechanochemistry.
Area of Science:
- Biochemistry
- Enzyme kinetics
- Biophysical chemistry
Background:
- Enzymes function as molecular machines.
- Adenosine triphosphate (ATP) synthesis is crucial for cellular energy.
- Magnesium ions (Mg2+) are essential cofactors in many enzymatic reactions.
Purpose of the Study:
- To investigate the role of magnesium isotopes in enzymatic ATP synthesis.
- To explore the mechanochemistry of enzymes using isotope effects.
- To determine if ATP synthesis is a spin-dependent process.
Main Methods:
- Studying the activity of phosphorylating enzymes (ATP-synthase, phosphocreatine kinase, phosphoglycerate kinase) with different magnesium isotopes (24Mg, 25Mg, 26Mg).
- Analyzing the magnetic isotope effect (MIE) on enzyme activity.
- Investigating the magnetic field dependence of enzymatic phosphorylation.
Main Results:
- Enzymes utilizing 25Mg showed 2-3 times higher activity compared to those with 24Mg or 26Mg.
- The observed isotope effect was magnetic, not mass-dependent, confirming MIE.
- A spin-dependent ion-radical mechanism involving reversible electron transfer was proposed.
- Pyruvate kinase also exhibited similar magnetic isotope effects.
Conclusions:
- ATP synthesis by phosphorylating enzymes is a spin-dependent ion-radical process.
- The mechanochemistry of enzymes can be elucidated through magnetic isotope effects.
- Hyperfine coupling involving 25Mg plays a critical role in controlling ATP yield.
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