Radiolysis and radioracemization of 20 amino acids from the beginning of the Solar System

被引:0
作者
Franco Cataldo
Ornella Ursini
Giancarlo Angelini
Susana Iglesias-Groth
Arturo Manchado
机构
[1] Istituto Nazionale di Astrofisica,
[2] Osservatorio Astrofisico di Catania,undefined
[3] Lupi Chemical Research,undefined
[4] Istituto di Metodologie Chimiche,undefined
[5] CNR,undefined
[6] Instituto de Astrofísica de Canarias (IAC),undefined
[7] CSIC,undefined
来源
Rendiconti Lincei | 2011年 / 22卷
关键词
Astrochemistry; Amino acids; Radiolysis; Racemization; Optical activity; Origin of life;
D O I
暂无
中图分类号
学科分类号
摘要
A series of chiral amino acids in the levo form used in the current terrestrial biochemistry were irradiated in the solid and dry state with γ-radiation to a dose of 3.2 MGy which is the dose equivalent to that derived by radionuclide decay in comets and asteroids in 1.05 × 109 years at a depth >20 m. For each amino acids, the radiolysis degree and the radioracemization degree was measured, respectively by differential scanning calorimetry (DSC) and by optical rotatory dispersion (ORD) spectroscopy. From these measurements, a radiolysis rate constant kdsc and a radioracemization rate constant krac were determined for each amino acid and extrapolated to a dose of 14 MGy which corresponds to the expected total dose delivered by the natural radionuclides decay to all the organic molecules present in comets and asteroids in 4.6 × 109 years, the age of the Solar System. It is shown that all the amino acids studied survive a radiation dose of 3.2 MGy although part of them is lost in radiolytic processes. Similarly also the radioracemization process accompanying the radiolysis does not extinguish the initial enantiomeric enrichment. Even the extrapolation to 14 MGy corresponding to 4.6 × 109 years shows the partial survival of all amino acids studied and their enantiomeric enrichment. The knowledge of the radiolysis and radioracemization rate constants may permit the calculation of the original concentration of the amino acids at the times of the formation of the Solar System starting from the concentration found today in carbonaceous chondrites. Based on these results, it is not at all a surprise that amino acids have been found in meteorites and in measureable chiral excess. Furthermore, the amino acids showing the best level of radiolysis and radioracemization resistance are just those commonly found in enantiomeric enrichment in meteorites.
引用
收藏
页码:81 / 94
页数:13
相关论文
共 79 条
[1]  
Bonner WA(1979)The radioracemization of amino acids by ionizing radiation: geochemical and cosmochemical implications Origins Life Evol Biosph 9 279-290
[2]  
Blair NE(2007)Gamma radiolysis of chiral terpenes: α(+)pinene and α(-)pinene J Radioanal Nucl Chem 272 82-90
[3]  
Lemmon RM(2007)Radiation-induced racemization and amplification of chirality: implications for comets and meteorites Int J Astrobiol 6 1-10
[4]  
Cataldo F(2009)Stability of C Mon Not R Astronom Soc 394 615-623
[5]  
Cataldo F(2010) and C Radiat Phys Chem 80 57-65
[6]  
Cataldo F(2010) fullerene toward corpuscular and gamma radiation J Radioanal Nucl Chem 287 573-580
[7]  
Strazzulla G(2000)Solid state radiolysis of amino acids in an astrochemical perspective Icarus 145 272-281
[8]  
Iglesias-Groth S(2003)Solid state radiolysis of sulphur-containing amino acids: cysteine, cystine and methionine Celest Mech Dyn Astron 87 157-189
[9]  
Cataldo F(2011)Racemization of meteoric amino acids Mon Not Roy Astronom Soc 410 1447-1453
[10]  
Angelini G(2008)Tidal heating and convection in the medium sized icy satellites Radiat Phys Chem 77 1160-1163