scholarly journals The Reaction of Aminonitriles with Aminothiols: A Way to Thiol-Containing Peptides and Nitrogen Heterocycles in the Primitive Earth Ocean

Life ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 47 ◽  
Author(s):  
Ibrahim Shalayel ◽  
Seydou Coulibaly ◽  
Kieu Ly ◽  
Anne Milet ◽  
Yannick Vallée
Keyword(s):  
Hydrogen Cyanide ◽  
Early Stage ◽  
Theoretical Calculations ◽  
Membered Ring ◽  
Small Peptides ◽  
Primitive Earth ◽  
Peptide Bonds ◽  
Heterocyclic Molecules ◽  
Strecker Reaction ◽  
Life On Earth

The Strecker reaction of aldehydes with ammonia and hydrogen cyanide first leads to α-aminonitriles, which are then hydrolyzed to α-amino acids. However, before reacting with water, these aminonitriles can be trapped by aminothiols, such as cysteine or homocysteine, to give 5- or 6-membered ring heterocycles, which in turn are hydrolyzed to dipeptides. We propose that this two-step process enabled the formation of thiol-containing dipeptides in the primitive ocean. These small peptides are able to promote the formation of other peptide bonds and of heterocyclic molecules. Theoretical calculations support our experimental results. They predict that α-aminonitriles should be more reactive than other nitriles, and that imidazoles should be formed from transiently formed amidinonitriles. Overall, this set of reactions delineates a possible early stage of the development of organic chemistry, hence of life, on Earth dominated by nitriles and thiol-rich peptides (TRP).

scholarly journals The Impact of Spaceflight and Microgravity on the Human Islet-1+ Cardiovascular Progenitor Cell Transcriptome

2021 ◽  
Vol 22 (7) ◽  
pp. 3577
Author(s):  
Victor Camberos ◽  
Jonathan Baio ◽  
Ana Mandujano ◽  
Aida F. Martinez ◽  
Leonard Bailey ◽  
...  
Keyword(s):  
Early Stage ◽  
Space Station ◽  
Cardiovascular Development ◽  
Support Cell ◽  
Cell Transcriptome ◽  
Islet 1 ◽  
Life On Earth ◽  
The Impact ◽  
And Oxidative Stress ◽  
Insight Into

Understanding the transcriptomic impact of microgravity and the spaceflight environment is relevant for future missions in space and microgravity-based applications designed to benefit life on Earth. Here, we investigated the transcriptome of adult and neonatal cardiovascular progenitors following culture aboard the International Space Station for 30 days and compared it to the transcriptome of clonally identical cells cultured on Earth. Cardiovascular progenitors acquire a gene expression profile representative of an early-stage, dedifferentiated, stem-like state, regardless of age. Signaling pathways that support cell proliferation and survival were induced by spaceflight along with transcripts related to cell cycle re-entry, cardiovascular development, and oxidative stress. These findings contribute new insight into the multifaceted influence of reduced gravitational environments.

Factors affecting the hydrogen cyanide potential of forage sorghum.

1990 ◽  
Vol 41 (6) ◽  
pp. 1093 ◽  
Author(s):  
JL Wheeler ◽  
C Mulcahy ◽  
JJ Walcott ◽  
GG Rapp
Keyword(s):  
Water Stress ◽  
Light Intensity ◽  
Hydrogen Cyanide ◽  
Dry Matter ◽  
Early Stage ◽  
Phosphorus Fertilizer ◽  
Factors Affecting ◽  
Forage Sorghum ◽  
Plant Maturity ◽  
Selection For

The effect of seven factors, namely genotype, plant maturity, nitrogen fertilizer, phosphorus fertilizer, water stress, light intensity and temperature, on the hydrogen cyanide potential (HCNp) of forage sorghum was studied in three pot experiments. Fivefold differences occurred between genotypes in HCNp, with a breeder's line, X45106, selected for low HCNp having a maximum of 520 mg HCN kg-1 DM (dry matter) compared with 2300 and 2450 mg kg-1 DM for cvs Zulu and Silk respectively. In X45 106, HCNp (mg HCN kg-1 DM) declined curvilinearly with age d (days from sowing) (HCNp=8460- 320d+ 3.1d2) and linearly in Silk (HCNp = 9020 - 110d), but the decline in Zulu was not statistically significant. Nitrogen (equivalent to 200 kg ha-1 of N) increased HCN, (P< 0.001), but more so in full light (100 mg kg-1 compared with 1430 mg kg-1) than in 50% shade (190 mg kg-1 compared with 690 mg kg-1). In one experiment, acute water stress appeared to reduce HCNp, but this was confounded with the strong decline due to aging. In another study, acute water stress had no effect on HCNp. Neither the application of superphosphate nor change in light intensity, nor change in temperature had a direct significant effect on HCNp in these studies. Breeding and selection for low HCNp appears a promising approach to ensuring that sorghum plants will provide non-toxic forage from an early stage of growth.

scholarly journals Modulating structure and properties in organic chromophores: influence of azulene as a building block

2014 ◽  
Vol 5 (10) ◽  
pp. 3753-3760 ◽  
Author(s):  
Masahito Murai ◽  
Sung-Yu Ku ◽  
Neil D. Treat ◽  
Maxwell J. Robb ◽  
Michael L. Chabinyc ◽  
...  
Keyword(s):  
Building Block ◽  
Theoretical Calculations ◽  
Membered Ring ◽  
Structure And Properties ◽  
Organic Chromophores

The properties of isomeric azulene derivatives, substituted through the 5-membered ring, were examined using a combination of experimentation and theoretical calculations for a series of well-defined electroactive oligomers.

A Remarkable Titanium-Catalyzed Asymmetric Strecker Reaction using Hydrogen Cyanide at Room Temperature

2010 ◽  
Vol 352 (13) ◽  
pp. 2153-2158 ◽  
Author(s):  
Balamurugan Ramalingam ◽  
Abdul Majeed Seayad ◽  
Li Chuanzhao ◽  
Marc Garland ◽  
Kazuhiko Yoshinaga ◽  
...  
Keyword(s):  
Hydrogen Cyanide ◽  
Room Temperature ◽  
Strecker Reaction

Theoretical studies of model compounds of lathyrane-type diterpenes

2004 ◽  
Vol 82 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Yukimasa Terada ◽  
Tomoo Matsuura ◽  
Yukari Mori ◽  
Shosuke Yamamura
Keyword(s):  
Ab Initio ◽  
Molecular Mechanics ◽  
Molecular Orbital ◽  
Theoretical Calculations ◽  
Membered Ring ◽  
Orbital Method ◽  
Methyl Groups ◽  
Molecular Orbital Method ◽  
Stable Conformation ◽  
Semi Empirical

The conformation of the 11-membered ring of the lathyrane skeleton has been investigated using NMR spectra and theoretical calculations. Some other skeletons, such as jatrophane, jatrapholane, and tigliane, seem to be derived from this framework, and the conformation is important in connection with the configuration of the resultant diterpenes. The conformation of lathyrane is principally defined by the orientation of the two methyl groups; namely, the methyl groups on C1 and C6 directed above or below the ring plane. Theoretical calculations revealed that the predominant conformation is altered depending on the oxygen functional groups on the ring. As far as the bond lengths, bond angles, and dihedral angles are concerned, all calculation methods afforded reasonable results. In contrast, as regards conformational stability, only the ab initio molecular orbital method (RHF/6-31G*) predicted the most stable conformation, consistent with NOE experiments. On the other hand, the stable conformations predicted by the ab initio method (RHF/STO-3G), the semi-empirical molecular orbital method (MOPAC(PM3)), and the molecular mechanics calculations (MM3) did not necessarily agree with the conformers suggested by the NOE experiments.Key words: ab initio MO, semi-empirical MO, molecular mechanics, 11-membered ring conformation, NOE.

Chemical evolution toward the origin of life

2007 ◽  
Vol 79 (12) ◽  
pp. 2101-2117 ◽  
Author(s):  
Daniel Fitz ◽  
Hannes Reiner ◽  
Bernd Michael Rode
Keyword(s):  
Chemical Evolution ◽  
Rna World ◽  
Early Stage ◽  
Building Blocks ◽  
Point Of View ◽  
Peptide Formation ◽  
The Origin Of Life ◽  
Life On Earth ◽  
Primordial Earth ◽  
Rna And Dna

Numerous hypotheses about how life on earth could have started can be found in the literature. In this article, we give an overview about the most widespread ones and try to point out which of them might have occurred on the primordial earth with highest probability from a chemical point of view. The idea that a very early stage of life was the "RNA world" encounters crucial problems concerning the formation of its building blocks and their stability in a prebiotic environment. Instead, it seems much more likely that a "peptide world" originated first and that RNA and DNA took up their part at a much later stage. It is shown that amino acids and peptides can be easily formed in a realistic primordial scenario and that these biomolecules can start chemical evolution without the help of RNA. The origin of biohomochirality seems strongly related to the most probable formation of the first peptides via the salt-induced peptide formation (SIPF) reaction.

Interpretation of the C1s XPS Signal in Copper Phthalocyanine for Organic Photovoltaic Device Applications

2010 ◽  
Vol 1270 ◽  
Author(s):  
K. Nauka ◽  
Hou T. Ng ◽  
Eric G. Hanson
Keyword(s):  
Photoelectron Spectroscopy ◽  
Copper Phthalocyanine ◽  
Theoretical Calculations ◽  
Membered Ring ◽  
Organic Photovoltaic ◽  
High Electron ◽  
Linear Optics ◽  
Photovoltaic Devices ◽  
Light Fastness ◽  
Non Linear Optics

AbstractCopper phthalocyanine (CuPc) belongs to a class of small molecules offering particularly interesting advantages when employed in organic electronic devices. Because of its advantageous attributes like high thermal stability, inertness when exposed to acids or alkalis, relatively high electron conductivity, color and light fastness it has been employed in polymer photovoltaic devices as a unipolar dopants complementing the buckminsterfullerene (C60) acceptors and as a conductive buffer. Other organic applications include ambipolar OFETs and non-linear optics structures. X-ray photoelectron spectroscopy (XPS) has been commonly employed to monitor the quality of thin CuPc films. Although XPS analyses of CuPc have been done for over forty years there has not yet been agreement regarding interpretation of the major C1s signal, particularly in the case of non-stoichometric CuPc composition. This work presents systematic studies of the C1s signal of thin film deposits, fabricated using commercially available CuPc materials. It was found that composite C1s CuPc signal consists of five components: two related to the principal C positions within the CuPc macrocycle (C-C in 6-membered ring, C-C-N in 5-membered ring), two associated with shake-up transitions accompanying principal C transitions, and one due to mostly aliphatic impurities. Detailed analysis showed that the magnitude of shake-up peaks was approximately equal 10% to 12% of their principal transitions, in agreement with the theoretical calculations. Correspondingly, the C1s signal originating from the non-CuPc impurities quantitatively agreed with the IR attenuated total reflectance (ATR-IR) measurement of the C-H aliphatic vibrations originating from these impurities present within the CuPc layer. The proposed C1s interpretation has been successfully tested for a large number of commercial CuPc materials and provides a guideline for a routine XPS analysis of the CuPc in organic photovoltaic devices.

scholarly journals Conformational studies of aliphatic secondary ozonides (propene, 1-butene and 1-heptene) by means of FTIR spectroscopy

2006 ◽  
Vol 4 (4) ◽  
pp. 578-591 ◽  
Author(s):  
Ruta Bariseviciute ◽  
Justinas Ceponkus ◽  
Alytis Gruodis ◽  
Valdas Sablinskas
Keyword(s):  
Theoretical Calculations ◽  
Membered Ring ◽  
Aliphatic Chain ◽  
Equatorial Position ◽  
Ir Absorption ◽  
Stable Conformer ◽  
Gaseous Products ◽  
Ir Absorption Spectra ◽  
Secondary Ozonide ◽  
The One

AbstractOzonization reaction of simple alkenes was studied by means of FT infrared absorption gas spectroscopy. The reaction was performed at 95 K in neat films of the reactants. IR absorption spectra of the gaseous products were recorded. The spectra were analyzed combining experimental results with theoretical calculations performed at B3LYP 6-311++G (3df, 3pd) level. We found that among all theoretically predicted conformers of propene secondary ozonide, only one which has the O-O half-chair configuration for the five membered ring and the radical attached in the equatorial position was present in the sample. Samples of 1-butene and 1-heptene secondary ozonides consist from two conformers of very similar energy (ΔH=0.3 kJ/mol). The most stable conformer for both ozonides is the one with O-O half-chair configuration of the five membered ring and the radical attached in equatorial position and the aliphatic chain in gauche position. The second stable conformer has the aliphatic chain in anti position.

scholarly journals Recognition of protein-linked glycans as a determinant of peptidase activity

2017 ◽  
Vol 114 (5) ◽  
pp. E679-E688 ◽  
Author(s):  
Ilit Noach ◽  
Elizabeth Ficko-Blean ◽  
Benjamin Pluvinage ◽  
Christopher Stuart ◽  
Meredith L. Jenkins ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Peptide Bond ◽  
Peptidase Activity ◽  
Peptide Bonds ◽  
Crystallographic Structures ◽  
Covalently Linked ◽  
Biochemical Analyses ◽  
Life On Earth ◽  
Glycoprotein Degradation ◽  
Hydrolysis Of

The vast majority of proteins are posttranslationally altered, with the addition of covalently linked sugars (glycosylation) being one of the most abundant modifications. However, despite the hydrolysis of protein peptide bonds by peptidases being a process essential to all life on Earth, the fundamental details of how peptidases accommodate posttranslational modifications, including glycosylation, has not been addressed. Through biochemical analyses and X-ray crystallographic structures we show that to hydrolyze their substrates, three structurally related metallopeptidases require the specific recognition of O-linked glycan modifications via carbohydrate-specific subsites immediately adjacent to their peptidase catalytic machinery. The three peptidases showed selectivity for different glycans, revealing protein-specific adaptations to particular glycan modifications, yet always cleaved the peptide bond immediately preceding the glycosylated residue. This insight builds upon the paradigm of how peptidases recognize substrates and provides a molecular understanding of glycoprotein degradation.

scholarly journals Prebiotic Synthesis of Cysteine Peptides That Catalyze Peptide Ligation in Neutral Water

2020 ◽  
Author(s):  
Callum Foden ◽  
Saidul Islam ◽  
Christian Arturo Fernandez Garcia ◽  
Leonardo Maugeri ◽  
Tom Sheppard ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Chemical Synthesis ◽  
Prebiotic Synthesis ◽  
Biomimetic Synthesis ◽  
Strecker Reaction ◽  
Simple Chemical ◽  
Peptide Biosynthesis ◽  
Neutral Water ◽  
Life On Earth

<div>Peptides and the proteinogenic α-amino acids are essential to all life on Earth. Peptide biosynthesis is orchestrated by a complex suite of enzymes in extant biology, but this must have been predated by a simple chemical synthesis at the origins of life. α-Aminonitriles, the nitrile precursors of α-amino acids, are generally readily produced by Strecker reactions, but the origin of cysteine—the thiol-bearing amino acid—is not understood. The aminothiol moiety of cysteine is chemically incompatible with nitriles at physiological pH, therefore cysteine nitrile is not stable, and it is widely believed that cysteine was a biological invention and a late addition to the genetic code<sub>.</sub> Here, we report the first high-yielding, prebiotic synthesis of cysteine peptides. Our biomimetic synthesis converts serine to cysteine, by-passing the Strecker reaction of β-mercaptoacetaldehyde, but exploits nitrile–activated dehydroalanine synthesis at near-neutral pH. We additionally demonstrate the catalytic prowess of <i>N</i>-acylcysteines (and related peptides and thiols) in the organocatalytic synthesis of peptides and peptidyl amidines in neutral water. Thiol catalysis directly couples kinetically stable—but energy-rich—α-amidonitriles to proteinogenic amines, in a reaction that tolerates all twenty proteinogenic side chains. This is a rare, prebiotically plausible example of selective and efficient organocatalysis in water. Our results implicate cysteine derivatives and thiol-catalysis at the onset of evolution.</div>

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