Prebiotic Peptides: Molecular Hubs in the Origin of Life

Abstract

The fundamental roles that peptides and proteins play in today’s biology makes it almost indisputable that peptides were key players in the origin of life. Insofar as it is appropriate to extrapolate back from extant biology to the prebiotic world, one must acknowledge the critical importance that interconnected molecular networks, likely with peptides as key components, would have played in life’s origin. In this review, we summarize chemical processes involving peptides that could have contributed to early chemical evolution, with an emphasis on molecular interactions between peptides and other classes of organic molecules. We first summarize mechanisms by which amino acids and similar building blocks could have been produced and elaborated into proto-peptides. Next, non-covalent interactions of peptides with other peptides as well as with nucleic acids, lipids, carbohydrates, metal ions, and aromatic molecules are discussed in relation to the possible roles of such interactions in chemical evolution of structure and function. Finally, we describe research involving structural alternatives to peptides and covalent adducts between amino acids/peptides and other classes of molecules. We propose that ample future breakthroughs in origin-of-life chemistry will stem from investigations of interconnected chemical systems in which synergistic interactions between different classes of molecules emerge.

Shock Processing of Amino Acids Leading to Complex Structures—Implications to the Origin of Life

“…The formation of peptides from amino acids is thus one of the crucial steps in the origin of life as peptides can form self-assembling molecular structures and interact with other classes of biomolecules, such as nucleic acids, lipids, etc. and enhance their structure and function [6]. Peptides are essential and are the structural building blocks that form supramolecular structures, such as helices, sheets, globules, fibers and tubes that can be used to build the basic architecture of a living cell [7].…”

Mapping the Molecular Tree of Life using Assembly Spaces

“…The shortest assembly pathway to make adenine and thymine altogether is the one indicated by the black dashed arrows. (b) A molecular assembly tree for A, G, T, U and C, which can also be written as { [2], [10], [11], [12], [13] }, whose index is…”

“…The issue therefore arises about how the space of molecules can be effectively searched (1,2,8) and what constrains molecules to being possible (2,(9)(10)(11), because for most use cases the interesting areas of chemical space will be vanishingly small compared to the space of possibilities (9,(12)(13)(14)(15).…”

“…This is a significant problem since the structure of chemical space is thought to encode a great deal of important contingent information (1,2). This is because the current structure of observable chemical space is highly connected to the chemical space of biology, which itself has been selected and explored using evolution over the past 4 billion years on Earth (1,10,11,34). Our hypothesis is that the information used to assemble the molecules found in biology was produced by random selection and is conserved and reused by the various biochemical pathways across all biology.…”

pH-Dependent peptide bond formation by the selective coupling of α-amino acids in water

“…The widespread importance of the synthesis of amides lies not only in synthetic organic chemistry, [1][2][3] but also in long-standing efforts aimed at understanding the formation of peptides composed of a-amino acids in the origin of life. [4][5][6][7] Although the ''RNA world'' hypothesis is a popular working model for studying the origin of life, 8,9 peptides could have coexisted with RNA at the outset of life. This is suggested by the fact that a-amino acids and nucleotide building blocks might have had a common chemical origin.…”