A search for endogenous amino acids in martian meteorite ALH84001

Science

Volumn 279, Issue 5349, 1998, Pages 362-365

  Bada, Jeffrey L ^a   Glavin, Daniel P ^a   McDonald, Gene D ^b   Becker, Luann ^c  

^a UNIVERSITY OF CALIFORNIA   (United States)

^b CALIFORNIA INSTITUTE OF TECHNOLOGY   (United States)

^c UNIVERSITY OF HAWAII   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ALANINE; GLYCINE; SERINE;

ALH84001 METEORITE; AMINO ACID; MARTIAN METEORITE; METEORITE COMPOSITION;

AMINO ACID ANALYSIS; ARTICLE; METEOROLOGY; PRIORITY JOURNAL;

NASA DISCIPLINE EXOBIOLOGY; NON-NASA CENTER;

ALANINE; AMINO ACIDS; ASPARTIC ACID; CHROMATOGRAPHY, HIGH PRESSURE LIQUID; GLYCINE; MARS; METEOROIDS; SERINE; STEREOISOMERISM;

EID: 0032536039     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.279.5349.362     Document Type: Article

References (47)

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10. In 1970 the Murchison meteorite was reported to contain endogenous amino acids based on the observation that amino acids having a chiral C were racemic (D/L ratio = 1.0) within the limits of the measurements [K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); G. E. Pollack, C. Cheng, K. A. Kvenvolden, Geochim. Cosmochim. Acta 39, 1571 (1975)]. Subsequent analyses of Murchison indicated that some protein amino acids showed an apparent enrichment in the L enantiomers, but this was considered to be the result of terrestrial contamination rather than from some sort of abiotic enantiomeric resolution or enrichment process [M. H. Engel and B. Nagy, Nature 296, 837 (1982); J. L Bada et al., ibid. 301, 494 (1983)]. Recently, J. R. Cronin and S. Pizzarello [Science 275, 951 (1997)] found small L enantiomeric excesses (5 to 10%) in Murchison nonprotein amino acids not associated with terrestrial biochemistry. In general, whether the exclusive use of L amino acids in terrestrial biology was preordained or simply a matter of chance selection is still a matter of debate.
11. In 1970 the Murchison meteorite was reported to contain endogenous amino acids based on the observation that amino acids having a chiral C were racemic (D/L ratio = 1.0) within the limits of the measurements [K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); G. E. Pollack, C. Cheng, K. A. Kvenvolden, Geochim. Cosmochim. Acta 39, 1571 (1975)]. Subsequent analyses of Murchison indicated that some protein amino acids showed an apparent enrichment in the L enantiomers, but this was considered to be the result of terrestrial contamination rather than from some sort of abiotic enantiomeric resolution or enrichment process [M. H. Engel and B. Nagy, Nature 296, 837 (1982); J. L Bada et al., ibid. 301, 494 (1983)]. Recently, J. R. Cronin and S. Pizzarello [Science 275, 951 (1997)] found small L enantiomeric excesses (5 to 10%) in Murchison nonprotein amino acids not associated with terrestrial biochemistry. In general, whether the exclusive use of L amino acids in terrestrial biology was preordained or simply a matter of chance selection is still a matter of debate.
12. In 1970 the Murchison meteorite was reported to contain endogenous amino acids based on the observation that amino acids having a chiral C were racemic (D/L ratio = 1.0) within the limits of the measurements [K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); G. E. Pollack, C. Cheng, K. A. Kvenvolden, Geochim. Cosmochim. Acta 39, 1571 (1975)]. Subsequent analyses of Murchison indicated that some protein amino acids showed an apparent enrichment in the L enantiomers, but this was considered to be the result of terrestrial contamination rather than from some sort of abiotic enantiomeric resolution or enrichment process [M. H. Engel and B. Nagy, Nature 296, 837 (1982); J. L Bada et al., ibid. 301, 494 (1983)]. Recently, J. R. Cronin and S. Pizzarello [Science 275, 951 (1997)] found small L enantiomeric excesses (5 to 10%) in Murchison nonprotein amino acids not associated with terrestrial biochemistry. In general, whether the exclusive use of L amino acids in terrestrial biology was preordained or simply a matter of chance selection is still a matter of debate.
13. In 1970 the Murchison meteorite was reported to contain endogenous amino acids based on the observation that amino acids having a chiral C were racemic (D/L ratio = 1.0) within the limits of the measurements [K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); G. E. Pollack, C. Cheng, K. A. Kvenvolden, Geochim. Cosmochim. Acta 39, 1571 (1975)]. Subsequent analyses of Murchison indicated that some protein amino acids showed an apparent enrichment in the L enantiomers, but this was considered to be the result of terrestrial contamination rather than from some sort of abiotic enantiomeric resolution or enrichment process [M. H. Engel and B. Nagy, Nature 296, 837 (1982); J. L Bada et al., ibid. 301, 494 (1983)]. Recently, J. R. Cronin and S. Pizzarello [Science 275, 951 (1997)] found small L enantiomeric excesses (5 to 10%) in Murchison nonprotein amino acids not associated with terrestrial biochemistry. In general, whether the exclusive use of L amino acids in terrestrial biology was preordained or simply a matter of chance selection is still a matter of debate.
14. In 1970 the Murchison meteorite was reported to contain endogenous amino acids based on the observation that amino acids having a chiral C were racemic (D/L ratio = 1.0) within the limits of the measurements [K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); G. E. Pollack, C. Cheng, K. A. Kvenvolden, Geochim. Cosmochim. Acta 39, 1571 (1975)]. Subsequent analyses of Murchison indicated that some protein amino acids showed an apparent enrichment in the L enantiomers, but this was considered to be the result of terrestrial contamination rather than from some sort of abiotic enantiomeric resolution or enrichment process [M. H. Engel and B. Nagy, Nature 296, 837 (1982); J. L Bada et al., ibid. 301, 494 (1983)]. Recently, J. R. Cronin and S. Pizzarello [Science 275, 951 (1997)] found small L enantiomeric excesses (5 to 10%) in Murchison nonprotein amino acids not associated with terrestrial biochemistry. In general, whether the exclusive use of L amino acids in terrestrial biology was preordained or simply a matter of chance selection is still a matter of debate.
15. In 1970 the Murchison meteorite was reported to contain endogenous amino acids based on the observation that amino acids having a chiral C were racemic (D/L ratio = 1.0) within the limits of the measurements [K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); G. E. Pollack, C. Cheng, K. A. Kvenvolden, Geochim. Cosmochim. Acta 39, 1571 (1975)]. Subsequent analyses of Murchison indicated that some protein amino acids showed an apparent enrichment in the L enantiomers, but this was considered to be the result of terrestrial contamination rather than from some sort of abiotic enantiomeric resolution or enrichment process [M. H. Engel and B. Nagy, Nature 296, 837 (1982); J. L Bada et al., ibid. 301, 494 (1983)]. Recently, J. R. Cronin and S. Pizzarello [Science 275, 951 (1997)] found small L enantiomeric excesses (5 to 10%) in Murchison nonprotein amino acids not associated with terrestrial biochemistry. In general, whether the exclusive use of L amino acids in terrestrial biology was preordained or simply a matter of chance selection is still a matter of debate.
16. A. S. MacKenzie, S. C. Brassell, G. Eglinton, J. R. Maxwell, Science 217, 491 (1982); T. Ramdahl, Nature 306, 580 (1983); B. R. T. Simoneit, Applied Geochem. 5, 3 (1990).
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19. J. H. Hahn, R. Zenobi, J. L. Bada, R. N. Zare, Science 239, 1523 (1988); S. J. Clemett, C. R. Maechling, R. N. Zare, P. D. Swan, R. M. Walker, ibid. 262, 721 (1993); L. J. Allamandola, A. G. G. M. Tielens, J. R. Barker, Astrophys. J. 71, 733 (1989); L. D'hendecourt, Astron. Soc. Pac. Conf. Ser. 122, 129 (1997).
20. J. H. Hahn, R. Zenobi, J. L. Bada, R. N. Zare, Science 239, 1523 (1988); S. J. Clemett, C. R. Maechling, R. N. Zare, P. D. Swan, R. M. Walker, ibid. 262, 721 (1993); L. J. Allamandola, A. G. G. M. Tielens, J. R. Barker, Astrophys. J. 71, 733 (1989); L. D'hendecourt, Astron. Soc. Pac. Conf. Ser. 122, 129 (1997).
21. J. H. Hahn, R. Zenobi, J. L. Bada, R. N. Zare, Science 239, 1523 (1988); S. J. Clemett, C. R. Maechling, R. N. Zare, P. D. Swan, R. M. Walker, ibid. 262, 721 (1993); L. J. Allamandola, A. G. G. M. Tielens, J. R. Barker, Astrophys. J. 71, 733 (1989); L. D'hendecourt, Astron. Soc. Pac. Conf. Ser. 122, 129 (1997).
22. J. H. Hahn, R. Zenobi, J. L. Bada, R. N. Zare, Science 239, 1523 (1988); S. J. Clemett, C. R. Maechling, R. N. Zare, P. D. Swan, R. M. Walker, ibid. 262, 721 (1993); L. J. Allamandola, A. G. G. M. Tielens, J. R. Barker, Astrophys. J. 71, 733 (1989); L. D'hendecourt, Astron. Soc. Pac. Conf. Ser. 122, 129 (1997).
23. In the analytical method used, amino acids were derivatized by OPA/NAC (o-phthaldialdehyde/N-acetyl L-cysteine, both obtained from Fisher). The derivatives were separated by reversed-phase HPLC with fluorescence detection and identified by comparison of retention times with standards [M. Zhao and J. L. Bada, Nature 339, 463 (1989); J. Chromatogr. A690, 55 (1995); G. D. McDonald and J. L. Bada, Geochim. Cosmochim. Acta 59, 1179 (1995); K. L. F. Brinton and J. L. Bada, ibid. 60, 349 (1996); K. L. F. Brinton et al., Origins Life Evol. Biosphere, in press]. The reaction of α-dialkyl amino acids such as α-aminoisobutyric acid (AIB) with the OPA/NAC reagent requires longer to reach completion. Thus, we carried out derivatizations for 1 and 15 min to provide an additional way to confirm the presence of these amino acids.
24. In the analytical method used, amino acids were derivatized by OPA/NAC (o-phthaldialdehyde/N-acetyl L-cysteine, both obtained from Fisher). The derivatives were separated by reversed-phase HPLC with fluorescence detection and identified by comparison of retention times with standards [M. Zhao and J. L. Bada, Nature 339, 463 (1989); J. Chromatogr. A690, 55 (1995); G. D. McDonald and J. L. Bada, Geochim. Cosmochim. Acta 59, 1179 (1995); K. L. F. Brinton and J. L. Bada, ibid. 60, 349 (1996); K. L. F. Brinton et al., Origins Life Evol. Biosphere, in press]. The reaction of α-dialkyl amino acids such as α-aminoisobutyric acid (AIB) with the OPA/NAC reagent requires longer to reach completion. Thus, we carried out derivatizations for 1 and 15 min to provide an additional way to confirm the presence of these amino acids.
25. In the analytical method used, amino acids were derivatized by OPA/NAC (o-phthaldialdehyde/N-acetyl L-cysteine, both obtained from Fisher). The derivatives were separated by reversed-phase HPLC with fluorescence detection and identified by comparison of retention times with standards [M. Zhao and J. L. Bada, Nature 339, 463 (1989); J. Chromatogr. A690, 55 (1995); G. D. McDonald and J. L. Bada, Geochim. Cosmochim. Acta 59, 1179 (1995); K. L. F. Brinton and J. L. Bada, ibid. 60, 349 (1996); K. L. F. Brinton et al., Origins Life Evol. Biosphere, in press]. The reaction of α-dialkyl amino acids such as α-aminoisobutyric acid (AIB) with the OPA/NAC reagent requires longer to reach completion. Thus, we carried out derivatizations for 1 and 15 min to provide an additional way to confirm the presence of these amino acids.
26. In the analytical method used, amino acids were derivatized by OPA/NAC (o-phthaldialdehyde/N-acetyl L-cysteine, both obtained from Fisher). The derivatives were separated by reversed-phase HPLC with fluorescence detection and identified by comparison of retention times with standards [M. Zhao and J. L. Bada, Nature 339, 463 (1989); J. Chromatogr. A690, 55 (1995); G. D. McDonald and J. L. Bada, Geochim. Cosmochim. Acta 59, 1179 (1995); K. L. F. Brinton and J. L. Bada, ibid. 60, 349 (1996); K. L. F. Brinton et al., Origins Life Evol. Biosphere, in press]. The reaction of α-dialkyl amino acids such as α-aminoisobutyric acid (AIB) with the OPA/NAC reagent requires longer to reach completion. Thus, we carried out derivatizations for 1 and 15 min to provide an additional way to confirm the presence of these amino acids.
27. In the analytical method used, amino acids were derivatized by OPA/NAC (o-phthaldialdehyde/N-acetyl L-cysteine, both obtained from Fisher). The derivatives were separated by reversed-phase HPLC with fluorescence detection and identified by comparison of retention times with standards [M. Zhao and J. L. Bada, Nature 339, 463 (1989); J. Chromatogr. A690, 55 (1995); G. D. McDonald and J. L. Bada, Geochim. Cosmochim. Acta 59, 1179 (1995); K. L. F. Brinton and J. L. Bada, ibid. 60, 349 (1996); K. L. F. Brinton et al., Origins Life Evol. Biosphere, in press]. The reaction of α-dialkyl amino acids such as α-aminoisobutyric acid (AIB) with the OPA/NAC reagent requires longer to reach completion. Thus, we carried out derivatizations for 1 and 15 min to provide an additional way to confirm the presence of these amino acids.
28. The pieces were from split 251, parent 65 (for the sampling diagram, see http://www-curator.jsc.nasa.gov/ curator/antmet/marsmets/SampleSummary.htm). These pieces were selected by the meteorite curator at the Johnson Space Center (M. Lindstrom) for this study because they were enriched in carbonate globules. Before analysis, we inspected each piece with a microscope and found that they contained numerous pale amber colored, dark rimmed globules similar in appearance to the photograph of ALH84001 carbonate concretions published by J. W. Valley et al. [Science 275, 1633 (1997)]. The combined weights of the 1 M HCl-soluble residues [extracts A and B described in (12)] indicate that carbonates make up about 1 to 2% by weight of the bulk meteorite in our ALH84001 sample, which is in agreement with the carbonate amounts reported by others (for example, see D. W. Mittlefehldt, Meteoritics 29, 214 (1994), and A. H. Treiman, ibid. 30, 294 (1995)].
29. The pieces were from split 251, parent 65 (for the sampling diagram, see http://www-curator.jsc.nasa.gov/ curator/antmet/marsmets/SampleSummary.htm). These pieces were selected by the meteorite curator at the Johnson Space Center (M. Lindstrom) for this study because they were enriched in carbonate globules. Before analysis, we inspected each piece with a microscope and found that they contained numerous pale amber colored, dark rimmed globules similar in appearance to the photograph of ALH84001 carbonate concretions published by J. W. Valley et al. [Science 275, 1633 (1997)]. The combined weights of the 1 M HCl-soluble residues [extracts A and B described in (12)] indicate that carbonates make up about 1 to 2% by weight of the bulk meteorite in our ALH84001 sample, which is in agreement with the carbonate amounts reported by others (for example, see D. W. Mittlefehldt, Meteoritics 29, 214 (1994), and A. H. Treiman, ibid. 30, 294 (1995)].
30. The pieces were from split 251, parent 65 (for the sampling diagram, see http://www-curator.jsc.nasa.gov/ curator/antmet/marsmets/SampleSummary.htm). These pieces were selected by the meteorite curator at the Johnson Space Center (M. Lindstrom) for this study because they were enriched in carbonate globules. Before analysis, we inspected each piece with a microscope and found that they contained numerous pale amber colored, dark rimmed globules similar in appearance to the photograph of ALH84001 carbonate concretions published by J. W. Valley et al. [Science 275, 1633 (1997)]. The combined weights of the 1 M HCl-soluble residues [extracts A and B described in (12)] indicate that carbonates make up about 1 to 2% by weight of the bulk meteorite in our ALH84001 sample, which is in agreement with the carbonate amounts reported by others (for example, see D. W. Mittlefehldt, Meteoritics 29, 214 (1994), and A. H. Treiman, ibid. 30, 294 (1995)].
31. The pieces were from split 251, parent 65 (for the sampling diagram, see http://www-curator.jsc.nasa.gov/ curator/antmet/marsmets/SampleSummary.htm). These pieces were selected by the meteorite curator at the Johnson Space Center (M. Lindstrom) for this study because they were enriched in carbonate globules. Before analysis, we inspected each piece with a microscope and found that they contained numerous pale amber colored, dark rimmed globules similar in appearance to the photograph of ALH84001 carbonate concretions published by J. W. Valley et al. [Science 275, 1633 (1997)]. The combined weights of the 1 M HCl-soluble residues [extracts A and B described in (12)] indicate that carbonates make up about 1 to 2% by weight of the bulk meteorite in our ALH84001 sample, which is in agreement with the carbonate amounts reported by others (for example, see D. W. Mittlefehldt, Meteoritics 29, 214 (1994), and A. H. Treiman, ibid. 30, 294 (1995)].
32. 2O was removed (analyses indicated that there were no significant amino acid levels above blanks), then 1 ml of 1 M HCl (double distilled) was added and the sample left at room temperature overnight. The next day, the sample was centrifuged, and one-third of the 1 M HCl supernatant was placed in a tube, dried under vacuum, weighed, and desalted with Bio-Rad AG50W-X8 cation exchange resin before amino acid analysis to determine free amino acids (this is extract A). The remaining two-thirds of the supernatant was placed in another tube, dried under vacuum, weighed, and then subjected to vapor-phase HCl hydrolysis at 150°C for 3 hours [A. Tsugita et al., J. Biochem. 102, 1593 (1987); R. G. Keil and D. L. Kirchman, Mar. Chem. 33, 243 (1991)]. The sample was then dried under vacuum and desalted for amino acid analysis to determine bound amino acids (this is extract B). The undissolved residue from the 1 M HCl extraction was dried, weighed again, and subjected to vapor-phase HCl hydrolysis as described above. After removal of HCl under vacuum, the sample was extracted with 1 ml of water, and both supernatant and residue were dried and weighed. The water extract was then desalted and analyzed to determine amino acids not associated with carbonate in the original sample (this is extract C). All the final desalted residues from each of the extracts were suspended in 50 μl and analyzed by the HPLC OPA/NAC method described in (10). A diagram of the processing procedure will be provided on request.
33. 2O was removed (analyses indicated that there were no significant amino acid levels above blanks), then 1 ml of 1 M HCl (double distilled) was added and the sample left at room temperature overnight. The next day, the sample was centrifuged, and one-third of the 1 M HCl supernatant was placed in a tube, dried under vacuum, weighed, and desalted with Bio-Rad AG50W-X8 cation exchange resin before amino acid analysis to determine free amino acids (this is extract A). The remaining two-thirds of the supernatant was placed in another tube, dried under vacuum, weighed, and then subjected to vapor-phase HCl hydrolysis at 150°C for 3 hours [A. Tsugita et al., J. Biochem. 102, 1593 (1987); R. G. Keil and D. L. Kirchman, Mar. Chem. 33, 243 (1991)]. The sample was then dried under vacuum and desalted for amino acid analysis to determine bound amino acids (this is extract B). The undissolved residue from the 1 M HCl extraction was dried, weighed again, and subjected to vapor-phase HCl hydrolysis as described above. After removal of HCl under vacuum, the sample was extracted with 1 ml of water, and both supernatant and residue were dried and weighed. The water extract was then desalted and analyzed to determine amino acids not associated with carbonate in the original sample (this is extract C). All the final desalted residues from each of the extracts were suspended in 50 μl and analyzed by the HPLC OPA/NAC method described in (10). A diagram of the processing procedure will be provided on request.
34. K. L. F. Brinton and J. L. Bada, Geochim. Cosmochim. Acta 60, 349 (1996). The D/L ratios of aspartic acid and alanine indicate that even in pristine lunar soils, some of the detected amino acids are terrestrial contaminants. In addition, the detected endogenous amino acids in lunar soils are apparently not actually present in the soil itself, but are generated from a soil component (HCN?) during sample processing.
35. K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); J. R. Cronin and S. Pizzarello, Adv. Space Res. 3, 5 (1983).
36. K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); J. R. Cronin and S. Pizzarello, Adv. Space Res. 3, 5 (1983).
37. K. Kvenvolden et al., Nature 228, 923 (1970); K. Kvenvolden, J. G. Lawless, C. Ponnamperuma, Proc. Natl. Acad. Sci. U.S.A. 68, 486 (1971); J. R. Cronin and S. Pizzarello, Adv. Space Res. 3, 5 (1983).
38. For example, see E. R. D. Scott, A. Yamaguchi, A. N. Krot, Nature 387, 377 (1997) and references therein.
39. -12 mol or less, we were unable to confirm peak identification using HPLC and mass spectrometry.
40. D. W. Mittlefehldt and M. M. Linstrom, Geochim. Cosmochim. Acta 55, 77 (1991).
41. E. K. Gibson Jr. and F. F. Andrawes, Proc. Lunar Planet. Sci. Conf. 12 1223 (1980).
42. G. K. A. Oswald and G. de Q. Robin, Nature 245, 251 (1973); J. C. Ellis Evans and D. Wynn-Williams, ibid. 381, 644 (1996); A. P. Kapitsa et al., ibid., p. 684.
43. G. K. A. Oswald and G. de Q. Robin, Nature 245, 251 (1973); J. C. Ellis Evans and D. Wynn-Williams, ibid. 381, 644 (1996); A. P. Kapitsa et al., ibid., p. 684.
44. G. K. A. Oswald and G. de Q. Robin, Nature 245, 251 (1973); J. C. Ellis Evans and D. Wynn-Williams, ibid. 381, 644 (1996); A. P. Kapitsa et al., ibid., p. 684.
45. Radiocarbon and stable C isotopic measurements have shown that ALH84001 carbonates, especially those in the size range <250 μm, have experienced various amounts of terrestrial alteration [A. J. T. Jull, C. J. Eastoe, S. Cloudt, J. Geophys. Res. 102, 1663 (1997)].
46. A. J. T. Jull et al., Science 279, 366 (1997).
47. We thank the Meteorite Steering Group in association with NSF, NASA, and the Smithsonian Institution, as well as the meteorite curator M. Lindstrom at the NASA Johnson Space Center, for providing the samples. We thank K. Kvenvolden and H. Craig for providing the Murchison and Allan Hills ice samples, K. Brinton for helpful discussions, and J. Higbee for encouragement. Collection of the Allan Hills ice samples was supported by NSF Polar Programs grant DPP91-18494 to H. Craig. Supported by grants from the NASA Ancient Martian Meteorite Research Program and the NASA Specialized Center for Research and Training in Exobiology at University of California at San Diego.