Mechanistic Insight into Metal Ion-Catalyzed Transamination
Robert J Mayer1, Harpreet Kaur1, Sophia A Rauscher1
1University of Strasbourg, CNRS, ISIS UMR 7006, 67000 Strasbourg, France.
Journal of the American Chemical Society
|November 3, 2021
Summary
Metal ions can catalyze transamination reactions, a key biological process, under conditions relevant to life. This suggests a simpler evolutionary origin for metabolic pathways, predating complex enzymes and co-factors.
Area of Science:
- Biochemistry
- Chemical Biology
- Evolutionary Biology
Background:
- Enzyme and co-factor mediated reactions can occur without them, catalyzed by metal ions.
- Metabolic pathways may have evolved from inorganic catalysts to complex organocatalysts.
- Transamination mechanisms are well-studied with enzymes/co-factors but less so with metal ions at biological temperatures.
Purpose of the Study:
- Investigate which metal ions catalyze transamination under biologically relevant conditions (pH 7, 20-50 °C).
- Elucidate the detailed mechanism of metal ion-catalyzed transamination.
- Explore the evolutionary implications of metal ion catalysis in biological reactions.
Main Methods:
- Screening of various metal ions for transamination catalysis.
- Kinetic studies to determine reaction rates and orders.
- Stereochemical analysis to understand reaction pathways.
- Computational studies to model reaction mechanisms.
Main Results:
- Cu2+, Ni2+, Co2+, and V5+ identified as active catalysts under biological conditions.
- Cu2+ and Co2+ stabilize a key imine intermediate.
- V5+ accelerates the reaction by increasing imine acidity.
- Ni2+ exhibits both stabilizing and acidity-increasing effects to a lesser extent.
Conclusions:
- Metal ions efficiently catalyze transamination under biologically compatible conditions.
- Amino group transfer is feasible without enzymes or co-factors via direct metal ion catalysis.
- Findings support the hypothesis of early metabolic pathways utilizing inorganic catalysts.
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