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Perspective and Concepts: Chirality in Nineteenth Century Science
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Pasteur's chemical and crystallographic work is described. The article commences with a brief overview of related science (chemical structure, crystallography, optical activity) before and after 1848, the year of the discovery of molecular chirality and spontaneous resolution. Concerning this discovery, three separate and varying reports are described. These are: (i) the publications in the scientific literature, (ii) the early (auto)biographies and (iii) Pasteur's handwritten laboratory notebooks. The three versions give differing views on the topic. Subsequently all of Pasteur's crystallographic and chemical work is passed in review, a topic very rarely broached. Pasteur's view in later life on this part of his work is examined. The article concludes with a discussion of the term dissymmetry used by Pasteur.
Although Lord Kelvin first defined the word "chiral" in 1893-1894, references in the literature give dates varying from 1884 to 1904. He referred previously to hetero and homochiral in 1873 in a note that is now lost. Apparently overlooked have been his definitions of hetero and homochiral in a text that he coauthored in 1879. The etymology of these and other related neologisms is considered.
Classical mechanisms proposed for the transition from racemic geochemistry to homochiral biochemistry in terrestrial evolution generally ascribe to chance the particular handed choice of the L-amino acids and the D-sugars by self-replicating systems. The parity-violating weak neutral current interaction gives rise to an energy difference between a chiral molecule and its mirror-image isomer, resulting in a small stabilization of the L-amino acids and the L-peptides in the alpha-helix and the beta-sheet conformation relative to the corresponding enantiomer. The energy difference suffices to break the chiral symmetry of autocatalytic racemic reaction sequences in an open non-equilibrium system.
Louis Pasteur presented his historic memoir on the discovery of molecular chirality to the Académie des sciences in Paris on May 22nd, 1848. The literature, however, nearly completely ignores this date, widely claiming instead May 15th, 1848, which first surfaced in 1922 in Pasteur's collected works edited by his grandson Louis Pasteur Vallery-Radot. On May 21st, 1848, i.e., one day before Pasteur's presentation in Paris, his mother died in Arbois, eastern France. Informed at an unknown point in time that she was "very ill," Pasteur left for Arbois only after his presentation. Biographies of Pasteur by his son-in-law René Vallery-Radot or the grandson, and Pasteur's collected correspondence edited by the grandson are incomprehensibly laconic or silent about the historic presentation. While no definite conclusions are possible, the evidence strongly suggests a deliberate alteration of the record by the biographer relatives, presumably for fear of adverse public judgment of Pasteur for a real or perceived insensitivity to a grave family medical emergency. Such fear would have been in accord with their hagiographic portrayal of Pasteur, and the findings raise questions concerning the extent of their zeal in protecting his "demigod" image. Universal recognition of the true date of Pasteur's announcement of molecular chirality is long overdue.
- Prelog
Thèses de chimie et de physique, présentées à la Faculté des sciences de Paris, le 26 août 1847
- L Pasteur
Thèses de chimie et de physique, présentées à la Faculté des sciences de Paris, le 23 août 1847
- L Pasteur
Tableau comparatif des Résultats de la Cristallographie et de l’Analyse Chimique relativement a` la Classification des Minéraux
- R.-J Haüy
Cahiers de laboratoire. Held at the Bibliothèque nationale de France
- L Pasteur
Preface in Sur la Dissymétrie Moléculaire: Louis Pasteur; van’t Hoff
- J Jacques
- Mauskopf
- Thomson
Correspondance: 1840-1895 réunie et annotée par L. Pasteur Vallery-Radot
- L Pasteur
- G Letter
- Chappuis
- Strasbourg
Oeuvres de Pasteur; Pasteur Vallery-Radot, L
- L Pasteur