Sugar in the primordial soup The formose reaction and the origin of life
Content <ul><li>Life from the Soup </li></ul><ul><li>Proteins  versus  RNA </li></ul><ul><li>Prebiotic syntheses of amino ...
Life on Earth    4.6  10 9  yrs ago  –  Formation of Earth    3.5  10 9  yrs ago  –  Prokaryotic organisms Now      ...
What started life? What compounds were present in the beginning? What compounds/reactions are required now?
The primordial ”soup” CO 2 N 2 CO SO 2 CH 2 O CH 4 Note: no photosynthesis - no O 2 ! NH 3 HCN CH 3 CN CH 2 CHCN HCCCN NCC...
Natural products Aminoacids Steroids Terpenes Lipids Purines Polyketides Carbohydrates Alkaloids Pyrimidines
Some are more important! Aminoacids Steroids Terpenes Lipids Purines Polyketides Carbohydrates Alkaloids Pyrimidines
The essentials of (modern) life Proteins composed of amino acids catalyse reactions RNA composed of nucleobases, ribose an...
Which was first, RNA or proteins? Proteins –  superior catalysts, simple building blocks, stable RNA –  can be catalysts, ...
Protein aminoacid
Prebiotic amino acid syntheses S.L. Miller Science   117  (1952) 528-529 J. Am. Chem. Soc.   77  (1955) 2351-2361 glycine ...
RNA ribose nucleobase phosphodiester
Prebiotic nucleobase syntheses J. Oró,  Nature   191  (1961) 1193-1194
Common monosaccharides   aldopentoses aldohexoses ketohexose glucose mannose ribose arabinose fructose
Prebiotic carbohydrate synthesis: The Formose reaction A. Butlerow,  Liebigs Ann. Chem.   53  (1861) 295-298 O. Leow,  J. ...
Some of the reactions involved Cannizzaro de Bruyn-van Ekenstein Aldol condensation Retro-aldol
Cannizzaro reaction Cannizzaro,  Ann.   88  (1853) 129-
de Bruyn-van Ekenstein rearrangement de Bruyn,  Rec. Trav. Chim.  14 (1895) 150- Evans,  Chem. Rev.   31  (1942) 537-559
de Bruyn-van Ekenstein mechanism Glucose Mannose Fructose 1,2-Enediol
The first step... formate methanol glycolaldehyde
Aldol condensation glyceraldehyde
de Bruyn-van Ekenstein glyceraldehyde dihydroxyacetone
C 3 +C 1     C 2 +C 2
Autocatalytic cycle C 2 C 2 C 3 C 4 C 1 C 1 C 1 C 1 very slow fast
The result:
Sugars in formose (55% total yield of sugars) Aldopentoses 7% (1.4% ribose) Aldohexoses 18% Ketopentoses 8% Ketohexoses 18%
Open chain forms 0.3-0.7% 0.002-0.1% hexoses 8-22% 0.1-0.2% pentoses 100% 11-16% tetroses ketoses aldoses
Tautomers of D-ribose Cyclic forms (99,9%) Acyclic forms (0,1%)  -furanose  -furanose  -pyranose  -pyranose hydrate al...
Problems Much more hexoses than pentoses Very little ribose Racemic mixture of sugars
D-glyceraldehyde dihydroxyacetone D-sorbose 26% D-fructose 34% H.O.L. Fischer & E. Baer,  Helv. Chim. Acta   19  (1936) 51...
Glycolaldehyde phosphate 1 Müller et al.,  Helv. Chim. Acta   73  (1990) 1410
Glycolaldehyde phosphate 2
Extraterrestial compounds Aminoacids Carbohydrates Pyrimidines Purines 60 ppm 60 0.06 1.2
Aminoacids +12 not found in proteins Gly Ala Glu Val Pro Asp Leu
Carbohydrates + aldonic acids  & alditols Mannose Xylose Glucose Arabinose Dihydroxyacetone
Conclusion The basic building blocks of proteins and RNA can be prepared from compounds expected to be present on early Ea...
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Sugar in the Primordial Soup

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  • Title – introduction
  • Sugar in the Primordial Soup

    1. 1. Sugar in the primordial soup The formose reaction and the origin of life
    2. 2. Content <ul><li>Life from the Soup </li></ul><ul><li>Proteins versus RNA </li></ul><ul><li>Prebiotic syntheses of amino acids & nucleobases </li></ul><ul><li>Prebiotic synthesis of sugars </li></ul><ul><li>Sugar in space </li></ul><ul><li>Conclusion </li></ul>
    3. 3. Life on Earth  4.6  10 9 yrs ago – Formation of Earth  3.5  10 9 yrs ago – Prokaryotic organisms Now   1.2  10 9 yrs ago – Eukaryotic organisms  0.7  10 9 yrs ago – Multicellular organisms Prebiotic
    4. 4. What started life? What compounds were present in the beginning? What compounds/reactions are required now?
    5. 5. The primordial ”soup” CO 2 N 2 CO SO 2 CH 2 O CH 4 Note: no photosynthesis - no O 2 ! NH 3 HCN CH 3 CN CH 2 CHCN HCCCN NCCN H 2 O
    6. 6. Natural products Aminoacids Steroids Terpenes Lipids Purines Polyketides Carbohydrates Alkaloids Pyrimidines
    7. 7. Some are more important! Aminoacids Steroids Terpenes Lipids Purines Polyketides Carbohydrates Alkaloids Pyrimidines
    8. 8. The essentials of (modern) life Proteins composed of amino acids catalyse reactions RNA composed of nucleobases, ribose and phosphate carry genetic information
    9. 9. Which was first, RNA or proteins? Proteins – superior catalysts, simple building blocks, stable RNA – can be catalysts, complex building blocks, unstable but can replicate themselves
    10. 10. Protein aminoacid
    11. 11. Prebiotic amino acid syntheses S.L. Miller Science 117 (1952) 528-529 J. Am. Chem. Soc. 77 (1955) 2351-2361 glycine 2,1% alanine 1,7%
    12. 12. RNA ribose nucleobase phosphodiester
    13. 13. Prebiotic nucleobase syntheses J. Oró, Nature 191 (1961) 1193-1194
    14. 14. Common monosaccharides aldopentoses aldohexoses ketohexose glucose mannose ribose arabinose fructose
    15. 15. Prebiotic carbohydrate synthesis: The Formose reaction A. Butlerow, Liebigs Ann. Chem. 53 (1861) 295-298 O. Leow, J. prakt. Chem. 33 (1886) 321-351
    16. 16. Some of the reactions involved Cannizzaro de Bruyn-van Ekenstein Aldol condensation Retro-aldol
    17. 17. Cannizzaro reaction Cannizzaro, Ann. 88 (1853) 129-
    18. 18. de Bruyn-van Ekenstein rearrangement de Bruyn, Rec. Trav. Chim. 14 (1895) 150- Evans, Chem. Rev. 31 (1942) 537-559
    19. 19. de Bruyn-van Ekenstein mechanism Glucose Mannose Fructose 1,2-Enediol
    20. 20. The first step... formate methanol glycolaldehyde
    21. 21. Aldol condensation glyceraldehyde
    22. 22. de Bruyn-van Ekenstein glyceraldehyde dihydroxyacetone
    23. 23. C 3 +C 1  C 2 +C 2
    24. 24. Autocatalytic cycle C 2 C 2 C 3 C 4 C 1 C 1 C 1 C 1 very slow fast
    25. 25. The result:
    26. 26. Sugars in formose (55% total yield of sugars) Aldopentoses 7% (1.4% ribose) Aldohexoses 18% Ketopentoses 8% Ketohexoses 18%
    27. 27. Open chain forms 0.3-0.7% 0.002-0.1% hexoses 8-22% 0.1-0.2% pentoses 100% 11-16% tetroses ketoses aldoses
    28. 28. Tautomers of D-ribose Cyclic forms (99,9%) Acyclic forms (0,1%)  -furanose  -furanose  -pyranose  -pyranose hydrate aldehyde
    29. 29. Problems Much more hexoses than pentoses Very little ribose Racemic mixture of sugars
    30. 30. D-glyceraldehyde dihydroxyacetone D-sorbose 26% D-fructose 34% H.O.L. Fischer & E. Baer, Helv. Chim. Acta 19 (1936) 519-532
    31. 31. Glycolaldehyde phosphate 1 Müller et al., Helv. Chim. Acta 73 (1990) 1410
    32. 32. Glycolaldehyde phosphate 2
    33. 33. Extraterrestial compounds Aminoacids Carbohydrates Pyrimidines Purines 60 ppm 60 0.06 1.2
    34. 34. Aminoacids +12 not found in proteins Gly Ala Glu Val Pro Asp Leu
    35. 35. Carbohydrates + aldonic acids & alditols Mannose Xylose Glucose Arabinose Dihydroxyacetone
    36. 36. Conclusion The basic building blocks of proteins and RNA can be prepared from compounds expected to be present on early Earth. The conditions to make them are incompatible, i.e. they can not be formed under the same reaction conditions and in the same place. The strongest proof that they could have been formed prebiotically is their presence in extraterrestrial matter.

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