Prebiotic aqueous reactions catalyzed by native nickel without hydrogen

Area of Science:

• Biochemistry
• Astrobiology
• Enzyme Catalysis

Background:

• Nickel is a rare transition metal in enzymes, yet crucial for carbon and energy metabolism in acetogens and methanogens via the acetyl-CoA pathway.
• The acetyl-CoA pathway is considered the most ancient CO₂ fixation pathway, with recent studies suggesting Ni⁰ can catalyze its reactions nonenzymatically.

Purpose of the Study:

• To investigate the catalytic and reductive capabilities of Ni⁰ in nonenzymatic redox reactions relevant to early metabolism.
• To explore Ni⁰'s potential to catalyze reactions without proteins, cofactors, or sulfur.

Main Methods:

• Studied Ni⁰ as a catalyst and reductant in aqueous solutions at 25-100 °C.
• Examined the conversion of 2-oxo acids to 2-hydroxy acids and amino acids in the presence of ammonia.
• Investigated Ni⁰'s role in the fumarate reductase reaction.

Main Results:

• Ni⁰ effectively converts 2-oxo acids to 2-hydroxy acids and, with ammonia, to amino acids without requiring H₂.
• Ni⁰ functions as a catalyst and reductant for the fumarate reductase reaction.
• Demonstrated Ni⁰'s ability to catalyze metabolic reactions under mild conditions without biological components.

Conclusions:

• Ni⁰ possesses broad catalytic activity and substrate specificity, mimicking ancient metabolic functions.
• These findings support the role of Ni⁰ as a key abiotic catalyst in the origin of metabolism.
• Expands the understanding of Ni⁰'s catalytic repertoire in prebiotic chemistry and early life.