Neutron Diffraction Structure of (2R,3R)-l -(−)-[2-D]Carnitine Tetrachloroaurate, [(CH3)3N-CH2-CHOH-CHD-COOH]+[AuCl4]-: Determination of the Absolute Stereochemistry of the Crotonobetaine-to-Carnitine Transformation Catalyzed by l -Carnitine Dehydratase from Escherichia coli
| Autor: | Wim T. Klooster, Fred Brewer, Sasha Englard, André Schreiber, Hermann Seim, Roy S. Lu, Tobias Metzenthin, Thomas F. Koetzle, Hans Peter Kleber, Frank Lutz, Robert Bau |
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| Rok vydání: | 1997 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 119:12055-12060 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/ja972105g |
| Popis: | Single-crystal neutron diffraction has been used to determine the stereochemical course of the hydration of trans-crotonobetaine to l-(−)-carnitine by the enzyme l-carnitine dehydratase. Firstly, an X-ray analysis of the undeuterated carnitinium salt [(CH3)3N-CH2-CH(OH)-CH2-COOH]+[AuCl4]- confirmed that the absolute configuration at the C3 position of l-(−)-carnitine (the CHOH group) is indeed R. This was accomplished using the gold atom as an anomalously-scattering source. Then stereospecifically deuterated l-(−)-[2-D] carnitine was prepared by the hydration of trans-crotonobetaine in D2O using purified l-carnitine dehydratase from Escherichia coli. The subsequent neutron analysis of deuterated [(CH3)3N-CH2-CH(OH)-CH2-COOH]+ [AuCl4]- revealed that the CHD group at position C2 also had the absolute R configuration, thus establishing that the addition of D2O across the CC double bond of trans-crotonobetaine proceeds by a stereospecific syn pathway. In contrast, all other hydration−dehydration reactions exa... |
| Databáze: | OpenAIRE |
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