Proteinoid

Proteinoid

Proteinoids, or thermal proteins, are protein-like molecules formed inorganically from amino acids. Some theories of abiogenesis propose that proteinoids were a precursor to the first living cells.

The inorganic polymerization of amino acids into proteins through the formation of peptide bonds was thought to occur only at temperatures over 140°C. However, the biochemist Sidney Walter Fox and his co-workers discovered that phosphoric acid acted as a catalyst for this reaction. They were able to form protein-like chains from a mixture of 18 common amino acids at only 70°C in the presence of phosphoric acid, and dubbed these protein-like chains proteinoids. Fox later found proteinoids similar to those he had created in his laboratory in lava and cinders from Hawaiian volcanic vents and determined that the amino acids present polymerized due to the heat of escaping gases and lava. Other catalysts have since been found; one of them, amidinium carbodiimide, is formed in primitive Earth experiments and is effective in dilute aqueous solutions.

When present in certain concentrations in aqueous solutions, proteinoids form small structures called microspheres or protocells. This is because some of the amino acids incorporated into proteinoid chains are more hydrophobic than others, and so proteinoids cluster together like droplets of oil in water. Many argue that these are not themselves alive in the traditional sense, but these structures exhibit many of the characteristics of cells accepted as living cells:

#a film-like outer wall.
#osmotic swelling and shrinking.
#budding.
#binary fission (dividing into two daughter microspheres).
#streaming movement of internal particles.

It is thought that the microspheres may have provided a cell compartment within which biochemistry could have become concentrated and protected from the outside environment during the process of chemical evolution.

Proteinoid microspheres are today being considered for use in pharmaceuticals, providing microscopic biodegradable capsules in which to package drugs for delivery to a specific region in the patient's body.


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Look at other dictionaries:

  • proteinoid — proteinoid. См. протеиноид. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • proteinoid — [prō′tēnoid΄, prōt′ēnoid΄] n. any of a group of synthetic, proteinlike polymers formed from amino acids subjected to heat and other conditions such as may have prevailed on earth billions of years ago; primordial protein …   English World dictionary

  • proteinoid — proteinoidas statusas T sritis chemija apibrėžtis Polipeptidas, gautas iš aminorūgščių terminės kondensacijos būdu. atitikmenys: angl. proteinoid rus. протеиноид …   Chemijos terminų aiškinamasis žodynas

  • proteinoid — /proh tee noyd , tee euh /, n. Biochem. a polymer of amino acids resembling a biological polypeptide but formed abiotically: suggested as a possible intermediate in protein development during primitive earth conditions. [1955 60; PROTEIN + OID] * …   Universalium

  • proteinoid — noun A polypeptide formed abiotically from by heating a mixture of amino acids …   Wiktionary

  • proteinoid — pro·tein·oid prō .tē .nȯid, prōt ē ə .nȯid, prōt ən .ȯid n any of various polypeptides which can be obtained by suitable polymerization of mixtures of amino acids …   Medical dictionary

  • proteinoid — pro·tein·oid …   English syllables

  • proteinoid — ˈprōˌtēˌnȯid, ˈprōtənˌȯid, ˈprōd.ēə̇ˌnȯid noun ( s) Etymology: protein + oid (I) : any of various polypeptides which can be obtained by suitable polymerization of mixtures of amino acids …   Useful english dictionary

  • proteinoid droplets — Membrane bounded droplets supposed to have been formed in ‘primaeval soup’ as an early stages in the evolution of cells …   Dictionary of molecular biology

  • протеиноид — proteinoid протеиноид. Полимер аминокислот с молекулярной массой до 10 кД, образуемый при нагревании до 70oС смеси из 18 аминокислот в присутствии фосфорной кислоты (имитация абиотических условий Земли); П. могут расщепляться протеазами, служить… …   Молекулярная биология и генетика. Толковый словарь.

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