scholarly journals Worlds in Collision and the Origin of Life

2019 ◽  
Author(s):  
Rainer Kühne
Keyword(s):  
Amino Acids ◽  
Gamma Ray ◽  
Rna World ◽  
Ice Age ◽  
Small Peptides ◽  
Primitive Earth ◽  
Asteroid Impact ◽  
The Earth ◽  
Terrestrial Life ◽  
Unicellular Organisms

Earth and Moon were formed 4.6 billion years ago by the collision of the two protoplanets Gaia and Theia. Afterwards the Earth formed a crust where colliding comets provided the water of the oceans. This Hadean Eon was terminated 3.9 billion years ago during the Late Heavy Bombardment when an eccentric orbit of Jupiter caused a bombardment of the Earth by asteroids. Soon thereafter, 3.8 billion years ago, there is geochemical evidence of terrestrial life which performed photosynthesis. The terrestrial life witnessed and survived several cataclysms including the snowball Earth 760 to 580 million years ago, an ice age 440 million years ago which was possibly caused by a gamma-ray burst, and an asteroid impact 65 million years ago which generated the Chicxulub crater and contributed to the extinction of the dinosaurs. The 1908 Tunguska explosion was caused by a small stony asteroid. Amino acids, purines, pyrimidines and sugars, but no proteins, nucleotides or extraterrestrial unicellular organisms were detected in meteorites. This argues against the hypothesis of panspermia. The synthesis of amino acids, small peptides, purines and pyrimidine ribonucleotides under conditions of the primitive Earth (Stanley Miller experiments) and the polymerization of RNA nucleotides on clay minerals suggests that viroids and an RNA world could have existed during the Hadean Eon.

Comets and Life on the Primitive Earth

1997 ◽  
Vol 161 ◽  
pp. 97-120 ◽  
Author(s):  
Juan Orò ◽  
Cristiano B. Cosmovici
Keyword(s):  
Amino Acids ◽  
Prebiotic Synthesis ◽  
External Source ◽  
Primitive Earth ◽  
Molecular Precursors ◽  
The Earth ◽  
Biochemical Compounds ◽  
Comet Halley ◽  
The Impact ◽  
Cometary Origin

AbstractComets may have contributed substantial amounts of water, volatiles and organic precursors such as HCN for the synthesis of biochemical compounds on the primitive Earth. This suggestion followed closely the prebiotic synthesis of adenine, purines and amino acids from HCN. Recent studies on the terrestrial heavy noble gases provide evidence that comets are the principal external source of Earth’s volatiles. During the encounter of comet Halley strong jets of CN, C2, C3and NH2were measured from Earth observatories, and by spacecraft mass spectrometry HCN, formaldehyde, adenine and many other organic compounds were detected, except amino acids. Obviously the latter require liquid water for their formation. Therefore upon capture of comets by the Earth, and melting of the frozen water, the synthesis of most biochemical compounds could take place readily. The detection of water, HCN and other organics of cometary origin after the impact of Comet SL-9 with Jupiter demonstrated the capability of survival of these molecules even after catastrophic events. Thus on the Earth HCN could be converted into purines, cyanacetylene, after hydration and condensation with urea, into pyrimidines, and formaldehyde into monosaccharides. In the presence of phosphates, which have been detected in cometary IDPs, nucleotides could also be synthesized. In conclusion, comets probably provided the necessary molecular precursors for the generation of life on the Earth.

Homochirality as the Signature of Extra-Terrestrial Life

1997 ◽  
Vol 161 ◽  
pp. 505-510
Author(s):  
Alexandra J. MacDermott ◽  
Laurence D. Barron ◽  
Andrè Brack ◽  
Thomas Buhse ◽  
John R. Cronin ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Optical Rotation ◽  
Physical Origin ◽  
Natural Choice ◽  
Rosetta Mission ◽  
Terrestrial Life ◽  
Subsurface Layers ◽  
Solar System Bodies ◽  
Origin Of Homochirality

AbstractThe most characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. We therefore suggest that a search for extra-terrestrial life can be approached as a Search for Extra- Terrestrial Homochirality (SETH). The natural choice for a SETH instrument is optical rotation, and we describe a novel miniaturized space polarimeter, called the SETH Cigar, which could be used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. We believe that homochirality may be found in the subsurface layers on Mars as a relic of extinct life, and on other solar system bodies as a sign of advanced pre-biotic chemistry. We discuss the chiral GC-MS planned for the Roland lander of the Rosetta mission to a comet and conclude with theories of the physical origin of homochirality.

LITTLE ICE AGE IN THE EARTH HISTORY AND ITS POSSIBLE REASONS

2020 ◽  
Vol 42 (1) ◽  
pp. 4-12
Author(s):  
Valeriy Fedorov ◽  
Denis Frolov
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Earth History ◽  
The Earth

Magnetic separation of amino acids by gold/iron-oxide composite nanoparticles synthesized by gamma-ray irradiation

2005 ◽  
Vol 293 (1) ◽  
pp. 106-110 ◽  
Author(s):  
Takuya Kinoshita ◽  
Satoshi Seino ◽  
Yoshiteru Mizukoshi ◽  
Yohei Otome ◽  
Takashi Nakagawa ◽  
...  
Keyword(s):  
Amino Acids ◽  
Iron Oxide ◽  
Magnetic Separation ◽  
Gamma Ray ◽  
Composite Nanoparticles ◽  
Oxide Composite ◽  
Gamma Ray Irradiation

scholarly journals Selective Recognition of Amino Acids and Peptides by Small Supramolecular Receptors

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 106
Author(s):  
Joana N. Martins ◽  
João Carlos Lima ◽  
Nuno Basílio
Keyword(s):  
Amino Acids ◽  
Selective Recognition ◽  
Great Promise ◽  
Macrocyclic Compounds ◽  
Synthetic Receptors ◽  
Small Peptides ◽  
Molecular Imprinted Polymers ◽  
Polymeric Systems ◽  
Physiological Conditions ◽  
Level Information

To this day, the recognition and high affinity binding of biomolecules in water by synthetic receptors remains challenging, while the necessity for systems for their sensing, transport and modulation persists. This problematic is prevalent for the recognition of peptides, which not only have key roles in many biochemical pathways, as well as having pharmacological and biotechnological applications, but also frequently serve as models for the study of proteins. Taking inspiration in nature and on the interactions that occur between several receptors and peptide sequences, many researchers have developed and applied a variety of different synthetic receptors, as is the case of macrocyclic compounds, molecular imprinted polymers, organometallic cages, among others, to bind amino acids, small peptides and proteins. In this critical review, we present and discuss selected examples of synthetic receptors for amino acids and peptides, with a greater focus on supramolecular receptors, which show great promise for the selective recognition of these biomolecules in physiological conditions. We decided to focus preferentially on small synthetic receptors (leaving out of this review high molecular weight polymeric systems) for which more detailed and accurate molecular level information regarding the main structural and thermodynamic features of the receptor biomolecule assemblies is available.

scholarly journals The conjugation of nonsteroidal anti-inflammatory drugs (NSAID) to small peptides for generating multifunctional supramolecular nanofibers/hydrogels

2013 ◽  
Vol 9 ◽  
pp. 908-917 ◽  
Author(s):  
Jiayang Li ◽  
Yi Kuang ◽  
Junfeng Shi ◽  
Yuan Gao ◽  
Jie Zhou ◽  
...  
Keyword(s):  
Amino Acids ◽  
Critical Concentration ◽  
Therapeutic Agents ◽  
Multiple Roles ◽  
Small Peptides ◽  
Covalent Linkage ◽  
Physiological Conditions ◽  
Racemic Ibuprofen ◽  
Inflammatory Drugs ◽  
Anti Inflammatory

Here we report supramolecular hydrogelators made of nonsteroidal anti-inflammatory drugs (NSAID) and small peptides. The covalent linkage of Phe–Phe and NSAIDs results in conjugates that self-assemble in water to form molecular nanofibers as the matrices of hydrogels. When the NSAID is naproxen (1), the resultant hydrogelator 1a forms a hydrogel at a critical concentration (cgc) of 0.2 wt % at pH 7.0. Hydrogelator 1a, also acting as a general motif, enables enzymatic hydrogelation in which the precursor turns into a hydrogelator upon hydrolysis catalyzed by a phosphatase at physiological conditions. The conjugates of Phe–Phe with other NSAIDs, such as (R)-flurbiprofen (2), racemic flurbiprofen (3), and racemic ibuprofen (4), are able to form molecular hydrogels, except in the case of aspirin (5). After the conjugation with the small peptides, NSAIDs exhibit improved selectivity to their targets. In addition, the peptides made of D-amino acids help preserve the activities of NSAIDs. Besides demonstrating that common NSAIDs are excellent candidates to promote aromatic–aromatic interaction in water to form hydrogels, this work contributes to the development of functional molecules that have dual or multiple roles and ultimately may lead to new molecular hydrogels of therapeutic agents for topical use.

scholarly journals Looking for the Gluon Condensation Signature in Protons Using the Earth-limb Gamma-Ray Spectra

2018 ◽  
Vol 868 (1) ◽  
pp. 2 ◽  
Author(s):  
Lei Feng ◽  
Jianhong Ruan ◽  
Fan Wang ◽  
Wei Zhu
Keyword(s):  
Gamma Ray ◽  
The Earth

Effects of small peptides or amino acids infused to a perfused area of the skin of Angora goats on mohair growth

2002 ◽  
Vol 80 (4) ◽  
pp. 1097-1104 ◽  
Author(s):  
R. Puchala ◽  
S. G. Pierzynowski ◽  
T. Wuliji ◽  
A. L. Goetsch ◽  
T. Sahlu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Small Peptides ◽  
Angora Goats
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