Proteinoides también referidos como proteínas térmicas, polímeros térmicos de aminoácidos[1] or thermal heterocomplex molecules from amino acids[2] are protein-like, aggregates formed abiotically by amino acids, nucleic acids and inorganic compounds. Sidney Fox developed a pioneering work in the thermal synthesis of polypeptides. Fox heated dry mixtures of 16 to 18 amino acids at 160-180º in a nitrogen atmosphere for a time period of several hours.[3] He noticed that the amino acids joined together by the loss of water molecules. Fox named the products resulting from his synthesis "proteinoids".[4] If proteinoids are dissolved in boiling water and the the solution is cooled the proteinoid molecules will coalesce to form microspheres.[5] The theory of abiogenesis proposed by Sidney Fox in the '60s, and who does not find many followers in the scientific community nowadays, stated that the agglomeration of proteinoid microspheres would have given rise to the precursors of the first living cells. Fox claimed that his proteinoid microspheres constitute protocells which were a vital link between the primordial chemical environment and true living cells.[6]
Comparison between true proteins and proteinoids
Spontaneous combinations of biomonomers may lead to proteinlike substances called proteinoids.[7] Proteinoids are not fully functioning proteins. The following table illustrates some of the major differences:
| Characteristic
|
Proteinoid
|
True protein
|
| Type of chain
|
Unnatural chains, “kinked” chains, even branched chains instead of being linear are produced[5][8] Secondary peptide linkages through the non-alpha carboxyl groups of aspartic and glutamic acids can be expected.[9]
|
Linear
|
| Peptide bonds
|
β, γ and ε peptide bonds largely predominate over α-peptide bonds[4]
|
α-peptide bonds
|
| Form of amino acids
|
Roughly the same number of D-amino acids (right-handed) and L-amino acids (left-handed).[4][5] Even if the experiment begins will all L-amino acids, some are converted to the right-handed form[8] and the L-amino acids undergo racemic[9]
|
Only L-amino acids
|
| Coding sequences
|
Amino acids bond together randomly.
|
Amino acids bond together based on the code contained in DNA.
|
| Pigments
|
Some amino acids are converted to colored substances, pigments, which are incorporated into the chains.[8]
|
Amino acids remain as is without converting to pigments
|
| Antigenicity tests
|
Show no antigenicity with guinea pig, rabbit or uterine strip tests[7]
|
Proteins (generally with a molecular weight of at least 8,000 Da) show antigenicity in tests
|
See also
Referencias
- ↑ Dose, Klaus; Rauchfuss, Horst (1972). «On the Electrophoretic Behavior of Thermal Polymers of Amino Acids». En Rohlfing, Duane L.. Molecular Evolution: Prebiological and Biological. Springer. p. 199-217. ISBN 978-1-4684-2021-0. http://link.springer.com/chapter/10.1007/978-1-4684-2019-7_17.
- ↑ Plantilla:Cite journal
- ↑ Plantilla:Cite book
- ↑ 4,0 4,1 4,2 Plantilla:Cite book
- ↑ 5,0 5,1 5,2 Plantilla:Cite book
- ↑ Plantilla:Cite journal
- ↑ 7,0 7,1 Plantilla:Cite book
- ↑ 8,0 8,1 8,2 Plantilla:Cite book
- ↑ 9,0 9,1 Plantilla:Cite book
