Dem IPB wird erneut ein beispielhaftes Handeln im Sinne einer chancengleichheitsorientierten Personal- und Organisationspolitik bescheinigt. Das Institut erhält zum 6. Mal in Folge das TOTAL E-QUALITY…
Die Plant Science Student Conference (PSSC) wird seit 20 Jahren im jährlichen Wechsel von Studierenden der beiden Leibniz-Institute IPK und IPB organisiert. Im Interview erläutern Christina Wäsch…
Hirata, K.; Poeaknapo, C.; Schmidt, J.; Zenk, M. H.;1,2-Dehydroreticuline synthase, the branch point enzyme opening the morphinan biosynthetic pathwayPhytochemistry651039-1046(2004)DOI: 10.1016/j.phytochem.2004.02.015
A synthase which oxidizes (S)-reticuline to 1,2-dehydroreticuline has been found to occur in seedlings of opium poppy (Papaver somniferum L.). Due to its instability, this enzyme could only be partly purified (ca. 5-fold enrichment). Partial characterization at this stage of purification showed that it does not need a redox cofactor and accepts both (S)-reticuline and (S)-norreticuline as substrates. [1-2H, 13C]-(R,S)-reticuline was enzymatically converted into [1-13C]-dehydroreticuline, which has been identified by mass spectrometry. Release of the hydrogen atom in position C-1 of the isoquinoline alkaloid during the oxidative conversion, was exploited as a sensitive assay system for this enzyme. The enzyme has a pH optimum of 8.75, a temperature optimum of 37 °C and the apparent KM value for the substrate reticuline was shown to be 117 μM. Moreover it could be demonstrated by sucrose density gradient centrifugation that the enzyme is located in vesicles of varying size. In combination with the previously discovered strictly stereoselective and NADPH dependent 1,2-dehydroreticuline reductase the detection of this enzyme, the 1,2-dehydroreticuline synthase, provides the necessary inversion of configuration and completes the pathway from two molecules of L-tyrosine via (S)-norcoclaurine to (R)-reticuline in opium poppy involving a total number of 11 enzymes.A synthase which oxidizes (S)-reticuline to 1,2-dehydroreticuline has been found to occur in seedlings of opium poppy (Papaver somniferum L.)
Publikation
Poeaknapo, C.; Fisinger, U.; Zenk, M. H.; Schmidt, J.;Evaluation of the mass spectrometric fragmentation of codeine and morphine after 13C-isotope biosynthetic labelingPhytochemistry651413-1420(2004)DOI: 10.1016/j.phytochem.2004.05.005
All major fragment ions of codeine and morphine were elucidated using LC–electrospray MS/MS and high resolution FT-ICR-MS combined with an IRMPD system. Nanogram quantities of labeled codeine were isolated and purified from Papaver somniferum seedlings, which were grown for up to 9 days in the presence of [ring-13C6]-l-tyrosine, [ring-13C6]-tyramine and [1,2-13C2], [6-O-methyl 13C]-(R,S)-coclaurine. The labeling degree of codeine up to 57% into morphinans was observed.