Juan Manuel González Mañas

Bio: Juan Manuel González Mañas is an academic researcher from University of the Basque Country. The author has contributed to research in topics: Dipeptide & Fatty acid. The author has an hindex of 2, co-authored 2 publications receiving 61 citations.

Fatty acids' double role in the prebiotic formation of a hydrophobic dipeptide

Abstract: In search of a connection between prebiotic peptide chemistry and lipid compartments, the reaction of a 5(4H)-oxazolone with leucinamide was extensively explored under buffered aqueous conditions, where diverse amphiphiles and surfactants could form supramolecular assemblies. Significant increases in yield and changes in stereoselectivity were observed when fatty acids exceeded their critical aggregation concentration, self-assembling into vesicles in particular. This effect does not take place below the fatty acid solubility limit, or when other anionic amphiphiles/surfactants are used. Data from fluorimetric and Langmuir trough assays, complementary to the main HPLC results reported here, demonstrate that the dipeptide product co-localizes with fatty acid bilayers and monolayers. Additional experiments in organic solvents suggest that acid-base catalysis operates at the water-aggregate interface, linked to the continuous proton exchange dynamics that fatty acids undergo at pH values around their effective pKa. These simple amphiphiles could therefore play a dual role as enhancers of peptide chemistry under prebiotic conditions, providing soft and hydrophobic organic domains through self-assembly and actively inducing catalysis at their interface with the aqueous environment. Our results support a systems chemistry approach to life's origin.

Correction: Fatty acids' double role in the prebiotic formation of a hydrophobic dipeptide

Abstract: Correction for ‘Fatty acids' double role in the prebiotic formation of a hydrophobic dipeptide’ by Sara Murillo-Sanchez et al., Chem. Sci., 2016, DOI: 10.1039/c5sc04796j.

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.

Molecular reactions at aqueous interfaces

Abstract: This Review aims to critically analyse the emerging field of chemical reactivity at aqueous interfaces. The subject has evolved rapidly since the discovery of the so-called ‘on-water catalysis’, alluding to the dramatic acceleration of reactions at the surface of water or at its interface with hydrophobic media. We review critical experimental studies in the fields of atmospheric and synthetic organic chemistry, as well as related research exploring the origins of life, to showcase the importance of this phenomenon. The physico-chemical aspects of these processes, such as the structure, dynamics and thermodynamics of adsorption and solvation processes at aqueous interfaces, are also discussed. We also present the basic theories intended to explain interface catalysis, followed by the results of advanced ab initio molecular-dynamics simulations. Although some topics addressed here have already been the focus of previous reviews, we aim at highlighting their interconnection across diverse disciplines, providing a common perspective that would help us to identify the most fundamental issues still incompletely understood in this fast-moving field. Enhanced chemical reactivity on-water has major implications in many fields, ranging from atmospheric to prebiotic chemistry. This Review analyses recent experimental and theoretical studies in this fast-moving research area and brings together some key findings across diverse fields.

Soft and dispersed interface-rich aqueous systems that promote and guide chemical reactions

Abstract: Although aqueous solutions are considered to be sustainable, environmentally friendly reaction media, their use is often limited by poor reactant solubility. This limitation can be overcome by converting aqueous solutions into soft, dispersed interface-rich systems such as polyelectrolyte solutions, micellar solutions, oil-in-water microemulsions or vesicle dispersions. All consist of homogeneously distributed dynamic structures that, in a fashion reminiscent of enzymes, provide local environments that are different from the bulk solution. The presence of soft, dispersed interface-rich structures leads to not only selective reaction accelerations but also changes in reaction pathways, whereby chemical reactions are guided towards desired products. Once again, the analogy to enzyme-catalysed transformations is enticing. In this Review, we illustrate the general concepts applied in such systems and illustrate them with selected examples, ranging from enzyme mimics, the preparation of conductive polymers and transition-metal-catalysed organic syntheses on the industrial scale to the chemistry of prebiotic systems. Aqueous media containing homogeneously distributed soft dynamic structures can promote a wide range of synthetic and degradative chemical reactions. This promotion is illustrated by selected examples from academia and industry, as well as from the field of prebiotic chemistry.

Prebiotic amino acids bind to and stabilize prebiotic fatty acid membranes

Abstract: The membranes of the first protocells on the early Earth were likely self-assembled from fatty acids. A major challenge in understanding how protocells could have arisen and withstood changes in their environment is that fatty acid membranes are unstable in solutions containing high concentrations of salt (such as would have been prevalent in early oceans) or divalent cations (which would have been required for RNA catalysis). To test whether the inclusion of amino acids addresses this problem, we coupled direct techniques of cryoelectron microscopy and fluorescence microscopy with techniques of NMR spectroscopy, centrifuge filtration assays, and turbidity measurements. We find that a set of unmodified, prebiotic amino acids binds to prebiotic fatty acid membranes and that a subset stabilizes membranes in the presence of salt and Mg2+ Furthermore, we find that final concentrations of the amino acids need not be high to cause these effects; membrane stabilization persists after dilution as would have occurred during the rehydration of dried or partially dried pools. In addition to providing a means to stabilize protocell membranes, our results address the challenge of explaining how proteins could have become colocalized with membranes. Amino acids are the building blocks of proteins, and our results are consistent with a positive feedback loop in which amino acids bound to self-assembled fatty acid membranes, resulting in membrane stabilization and leading to more binding in turn. High local concentrations of molecular building blocks at the surface of fatty acid membranes may have aided the eventual formation of proteins.