Protocellular Heme and Iron-Sulfur Clusters.

Area of Science:

• Astrobiology
• Biochemistry
• Geochemistry

Background:

• Iron is the most abundant transition metal on early Earth and crucial for modern biology.
• Understanding the role of metals in prebiotic chemistry is central to uncovering the origins of life.

Purpose of the Study:

• To investigate the plausibility of prebiotic iron complexes, specifically heme and iron-sulfur clusters, in mediating essential protocell chemistry.
• To explore the catalytic activities and potential roles of these iron complexes in early biochemical processes.

Main Methods:

• Laboratory experiments simulating prebiotic conditions.
• Spectroscopic analysis to identify and characterize iron complexes.
• Investigating catalytic activities, including peroxidase-like functions and redox potential tuning.

Main Results:

• Plausible UV-light-mediated pathways for heme and iron-sulfur cluster synthesis were identified.
• Heme, when complexed with amphiphiles, demonstrated catalytic activity in reducing hydrogen peroxide and synthesizing organic molecules.
• Iron-sulfur peptides exhibit a range of reduction potentials, potentially complementary to hemes, but their membrane association and prebiotic roles remain unclear.

Conclusions:

• Prebiotic heme and iron-sulfur clusters likely facilitated crucial chemical reactions for early protocells.
• The integration of iron-sulfur peptides into cellular metabolism may have occurred later with the evolution of compatible membranes.
• Further research is needed to fully elucidate the timing and mechanisms by which these iron complexes contributed to the origin of life and metabolism.