Interactions of iron-sulfur clusters with small peptides: insights into early evolution.

Favoring the stability of iron-sulfur clusters in hydrothermal vents could have been important for the origin of life. It has been postulated that small "nest" peptides with lengths between 3 and 6 residues could have been important to stabilize early iron-sulfur clusters. We present theoretical calculations exploring the sequence and conformational spaces of short peptides able to bind with high affinity the iron-sulfur cluster Fe(4)S(4). Our results indicate that it is unlikely to form stable complexes between Fe(4)S(4) and small peptides at the core of hydrothermal vents. The formation of these complexes is instead favored for peptides of at least 8 residues as they diffused together with the Fe(4)S(4) clusters toward lower temperature regions within the vent-associated temperature gradients.