Synthesis and Characterization of Amino Acid Decyl Esters as Early Membranes for the Origins of Life.

Understanding how membrane forming amphiphiles are synthesized and aggregate in prebiotic settings is required for understanding the origins of life on Earth 4 billion years ago. Amino acids decyl esters were prepared by dehydration of decanol and amino acid as a model for a plausible prebiotic reaction at two temperatures. Fifteen amino acids were tested with a range of side chain chemistries to understand the role of amino acid identity on synthesis and membrane formation.

The Prebiotic Kitchen: A Guide to Composing Prebiotic Soup Recipes to Test Origins of Life Hypotheses.

"Prebiotic soup" often features in discussions of origins of life research, both as a theoretical concept when discussing abiological pathways to modern biochemical building blocks and, more recently, as a feedstock in prebiotic chemistry experiments focused on discovering emergent, systems-level processes such as polymerization, encapsulation, and evolution. However, until now, little systematic analysis has gone into the design of well-justified prebiotic mixtures, which are needed to facilitate experimental replicability and comparison among researchers. This paper explores principles that should be considered in choosing chemical mixtures for prebiotic chemistry experiments by reviewing the natural environmental conditions that might have created such mixtures and then suggests reasonable guidelines for designing recipes.

The Grayness of the Origin of Life.

In the search for life beyond Earth, distinguishing the living from the non-living is paramount. However, this distinction is often elusive, as the origin of life is likely a stepwise evolutionary process, not a singular event. Regardless of the favored origin of life model, an inherent "grayness" blurs the theorized threshold defining life.

Partitioning of amino acids and proteins into decanol using phase transfer agents towards understanding life in non-polar liquids.

Water has many roles in the context of life on Earth, however throughout the universe, other liquids may be able to support the emergence of life. We looked at the ability of amino acids, peptides, a depsipeptide, and proteins to partition into a non-polar decanol phase, with and without the addition of a phase transfer agent. Partitioning evaluated using UV detection, or with HPLC coupled to either charged aerosol detection or ESI-MS.

Vesicle Self-Assembly of Monoalkyl Amphiphiles under the Effects of High Ionic Strength, Extreme pH, and High Temperature Environments.

Vesicles and other bilayered membranous structures can self-assemble from single hydrocarbon chain amphiphiles. Their formation and stability are highly dependent on experimental conditions such as ionic strength, pH, and temperature. The addition of divalent cations, for example, often results in the disruption of vesicles made of a single fatty acid species through amphiphile precipitation.

The Impact of Salts on Single Chain Amphiphile Membranes and Implications for the Location of the Origin of Life.

One of the key steps in the origins of life was the formation of a membrane to separate protocells from their environment. These membranes are proposed to have been formed out of single chain amphiphiles, which are less stable than the dialkyl lipids used to form modern membranes. This lack of stability, specifically for decanoate, is often used to refute ocean locations for the origins of life.

Synthesis of Lipophilic Guanine N-9 Derivatives: Membrane Anchoring of Nucleobases Tailored to Fatty Acid Vesicles.

Covalent or noncovalent surface functionalization of soft-matter structures is an important tool for tailoring their function and stability. Functionalized surfaces and nanoparticles have found numerous applications in drug delivery and diagnostics, and new functionalization chemistry is continuously being developed in the discipline of bottom-up systems chemistry. The association of polar functional molecules, e.

Prebiotic Vesicle Formation and the Necessity of Salts.

Self-assembly is considered one of the driving forces behind abiogenesis and would have been affected by the environmental conditions of early Earth. The formation of membranes is a key step in this process, and unlike large dialkyl membranes of modern cells the first membranes were likely formed from small single-chain amphiphiles, which are environment-sensitive. Fatty acids and their derivatives have been previously characterized in this role without concern for the concentrations of ionic solutes in the suspension.

Phototriggered DNA phosphoramidate ligation in a tandem 5'-amine deprotection/3'-imidazole activated phosphate coupling reaction.

We report the preparation and use of an N-methyl picolinium carbamate protecting group for applications in a phototriggered nonenzymatic DNA phosphoramidate ligation reaction. Selective 5'-amino protection of a modified 13-mer oligonucleotide is achieved in aqueous solution by reaction with an N-methyl-4-picolinium carbonyl imidazole triflate protecting group precursor. Deprotection is carried out by photoinduced electron transfer from Ru(bpy)(3)(2+) using visible light photolysis and ascorbic acid as a sacrificial electron donor.

Interactions between catalysts and amphiphilic structures and their implications for a protocell model.

One of the essential elements of any cell, including primitive ancestors, is a structural component that protects and confines the metabolism and genes while allowing access to essential nutrients. For the targeted protocell model, bilayers of decanoic acid, a single-chain fatty acid amphiphile, are used as the container. These bilayers interact with a ruthenium-nucleobase complex, the metabolic complex, to convert amphiphile precursors into more amphiphiles.

Analysis of advanced glycation endproducts in dairy products by isotope dilution liquid chromatography-electrospray tandem mass spectrometry. The particular case of carboxymethyllysine.

A fully validated multiple-transition recording isotope dilution liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantitative determination of N(epsilon)-carboxymethyllysine (CML) and lysine in dairy products is described. Internal standards were [N-1',2'-(13)C(2)]CML and [1,2,3,4,5,6-(13)C(6)-2,6-(15)N(2)]lysine, and the method was validated by evaluating the selectivity, linearity, precision (repeatability and reproducibility) and trueness, using both powder and liquid products. For liquid dairy products, the repeatability and reproducibility was 2.

Nucleobase mediated, photocatalytic vesicle formation from an ester precursor.

We report the use of photoinduced electron transfer to drive reductive cleavage of an ester to produce bilayer-forming molecules; specifically, visible photolysis in a mixture of a decanoic acid ester precursor, hydrogen donor molecules, and a ruthenium-based photocatalyst that employs a linked nucleobase (8-oxo-guanine) as an electron donor generates decanoic acid. The overall transformation of the ester precursor to yield vesicles represents the use of an external energy source to convert nonstructure forming molecules into amphiphiles that spontaneously assemble into vesicles. The core of our chemical reaction system uses an 8-oxo-G-Ru photocatalyst, a derivative of [tris(2,2'-bipyridine)-Ru(II)](2+).

Evaluating the extent of protein damage in dairy products: simultaneous determination of early and advanced glycation-induced lysine modifications.

An isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine lysine (Lys), N(epsilon)-fructosyllysine (FL), N epsilon-carboxymethyllysine (CML), and pyrraline (Pyr) in dairy products. The presented approach entails protein cleavage via enzymatic digestion to liberate the aforementioned compounds, which were then quantified using a stable isotope dilution assay. LC-MS/MS analysis was performed by positive electrospray ionization recording two transition reactions per analyte in selected reaction monitoring mode.

N(epsilon)-carboxymethyllysine-modified proteins are unable to bind to RAGE and activate an inflammatory response.

Advanced glycation endproducts (AGEs) containing carboxymethyllysine (CML) modifications are generally thought to be ligands of the receptor for AGEs, RAGEs. It has been argued that this results in the activation of pro-inflammatory pathways and diseases. However, it has not been shown conclusively that a CML-modified protein can interact directly with RAGE.

Studies on N-terminal glycation of peptides in hypoallergenic infant formulas: quantification of alpha-N-(2-furoylmethyl) amino acids.

To obtain information about the extent of the early Maillard reaction between the N-termini of peptides and lactose, alpha-N-(2-furoylmethyl) amino acids (FMAAs) were quantified together with epsilon-N-(2-furoylmethyl)lysine (furosine) in acid hydrolyzates of hypoallergenic infant formulas, conventional infant formulas, and human milk samples using RP-HPLC with UV-detection. FMAAs are formed during acid hydrolysis of peptide-bound N-terminal Amadori products (APs), and furosine is formed from the Amadori products of peptide-bound lysine. Unambiguous identification was achieved by means of LC/MS and UV-spectroscopy using independently prepared reference material.

From solution phase to "on-column" chemistry: trichloroacetimidate-based glycosylation promoted by perchloric acid-silica.

[reaction: see text] Activation of ester-protected glycosyl trichloroacetimidate donors by perchloric acid immobilized on silica afforded 1,2-trans disaccharides in 60-90% yields. Applying this approach to one-pot sequential glycosylation resulted in efficient syntheses of the N-linked glycan trimannoside and Le(X) and Le(A) trisaccharides in very good yield (76%, 62%, and 59% yields, respectively). Solution phase reactions were also translated to a solid phase format; priming the top of a standard silica chromatography column with perchloric acid immobilized on silica facilitated "on-column" glycosylation with subsequent "in situ" purification of products.