Coenzyme F430 from Methanogenic Bacteria: Complete Assignment of Configuration Based on an X-Ray Analysis of 12,13-Diepi-F430 Pentamethyl Ester and on NMR Spectroscopy |
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Authors: | Gerald Frber Walter Keller Christoph Kratky Berhard Jaun Andreas Pfaltz Christoh Spinner Andr Kobelt Albert Eschenmoser |
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Institution: | Gerald Färber,Walter Keller,Christoph Kratky,Berhard Jaun,Andreas Pfaltz,Christoh Spinner,André Kobelt,Albert Eschenmoser |
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Abstract: | The structure of a derivative of coenzyme F430 from methanogenic bacteria, the bromide salt of 12,13-diepi-F430 pentamethyl ester ( 5 , X = Br), was determined by X-ray structure analysis. It reveals a more pronounced saddle-shaped out-of-plane deformation of the macrocycle than any hydroporphinoid Ni complex investigated so far. The crystal structure confirms the constitution proposed for coenzyme F430 ( 2 ) and shows that in the epimer 5 , the three stereogenic centers in ring D, C(17), C(18), and C(19), have the (17S)-, (18S)-, and (19R)-configuration, respectively. Deuteration and 2D-NMR studies independently demonstrate that native coenzyme F430 (2) has the same configuration in ring D as the epimer 5 . Therefore, our original tentative assignment of configuration at C(19) and C(18) 1] has to be reversed. This completes the assignment of configuration for all stereogenic centers in coenzyme F430, which has the structure shown in Formula 2 . |
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