1979
DOI: 10.1016/0016-7037(79)90032-2
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The radioracemization of isovaline. Cosmochemical implications

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Cited by 19 publications
(8 citation statements)
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“…A large number of experiments have been performed to test this hypothesis, on a broad suite of amino acids, using several different radioactivity sources. The literature is extensive (see [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ] for a representative sampling), yielding either positive reports of small enantiomeric excesses (typically <1%) or products were determined to be racemic within measurement error. Definitive conclusions for the viability of this mechanism have proven elusive because of difficulties associated with measuring small enantiomeric excesses, but the preponderance of evidence suggests that β-decay can in fact lead to amino acid asymmetry, at least to a small extent (<1%), which would need to undergo subsequent amplification to match enantiomeric excess levels observed in meteorites.…”
Section: Origins Of Meteoritic Amino Acid Enantiomeric Excessesmentioning
confidence: 99%
See 1 more Smart Citation
“…A large number of experiments have been performed to test this hypothesis, on a broad suite of amino acids, using several different radioactivity sources. The literature is extensive (see [ 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ] for a representative sampling), yielding either positive reports of small enantiomeric excesses (typically <1%) or products were determined to be racemic within measurement error. Definitive conclusions for the viability of this mechanism have proven elusive because of difficulties associated with measuring small enantiomeric excesses, but the preponderance of evidence suggests that β-decay can in fact lead to amino acid asymmetry, at least to a small extent (<1%), which would need to undergo subsequent amplification to match enantiomeric excess levels observed in meteorites.…”
Section: Origins Of Meteoritic Amino Acid Enantiomeric Excessesmentioning
confidence: 99%
“…Radioactivity sources relevant to meteorite parent bodies include 60 Fe [ 109 , 110 ], which decays to 60 Ni via 60 Co, giving off two β-particles, an antineutrino, and Bremsstrahlung in the decay process. Nearly all of the reports in the literature have focused on proteinogenic amino acids, with only two related studies having been reported on isovaline, the only α-methyl amino acid studied [ 102 , 111 ]. Although it was shown that isovaline could be interconverted between enantiomers by irradiation, no net enantiomeric excesses were observed.…”
Section: Origins Of Meteoritic Amino Acid Enantiomeric Excessesmentioning
confidence: 99%
“…For the mechanism of racemization of amino acids lacking an -H atom, see: Pizzarello & Groy (2011). For the role that crystallization can play in the enrichment of l-isovaline, see: Glavin & Dworkin (2009); Bada (2009); Bonner et al (1979). For normal bond lengths and angles, see: Orpen (1993).…”
Section: Related Literaturementioning
confidence: 99%
“…However, little is known about the mechanism of racemization of amino acids lacking an alpha hydrogen atom (Pizzarello & Groy, 2011). The structure of isovaline given here can be used to examine the role that crystallization can play in the enrichment of L isovaline (Glavin & Dworkin 2009;Bada, 2009), and as a starting point in mechanistic studies of racemization mechanisms of isovaline (Bonner et al, 1979).…”
Section: S1 Commentmentioning
confidence: 99%
“…The cosmological, geochemical and paleontological implications of isovaline radioracemization were subsequently discussed in detail. 48,49 Radioracemization experiments were later extended 50,51 to include amino acids in the presence of both silica and clay surfaces, with the findings that such mineral surfaces rendered the amino acids even more vulnerable to radioracemization.It was pointed out 46 early in the above studies that radioracemization must exert a detrimental influence on the efficacy of the Vester-Ulbricht mechanism. Depending on the relative rates of formation of an excess of one enantiomer by enantioselective ␤-radiolysis compared to the rate of its radioracemization, it is clear that the latter effect could in principle nullify the former, particularly considering the enhancing role of mineral surfaces.…”
mentioning
confidence: 99%