Absolute configuration of 3-hydroxy acids formed by Stenotrophomonas maltophilia: application of multidimensional gas chromatography and circular dichroism spectroscopy. |
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Authors: | Kerstin Weil Hans-Ulrich Humpf Wilfried Schwab Peter Schreier |
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Institution: | Universit?t Würzburg, Lehrstuhl für Lebensmittelchemie, Am Hubland, D-97074 Würzburg, Germany. |
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Abstract: | The soil bacterium Stenotrophomonas maltophilia was found to transform various long-chain fatty acids selectively into 3-hydroxy fatty acids of shorter chain length. Their chiral evaluation was performed by multidimensional gas chromatography (MDGC) on modified cyclodextrin phase comparing the enantiodistribution of 1,3-diol formed without loss of stereochemical information from a representative microbial product with those of synthetic (3RS)- and (3S)-1,3-diols. Enantiomeric excesses of 84-98% (R) were determined for the microbially produced 3-hydroxy acids. In addition, the CD exciton chirality method was applied to determine their absolute configuration. Derivatization with 9-anthryldiazomethane and 2-naphthoylimidazole led to the required bichromophoric structures. Their CD spectra displayed a positive first Cotton effect around 254 nm and a negative second Cotton effect around 237 nm, which confirmed the (R)-configuration of the bacterial products. |
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Keywords: | Stenotrophomonas maltophilia bacteria biotransformation 3‐hydroxy acid absolute configuration multidimensional gas chromatography circular dichroism CD exciton chirality method |
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