43 酵素的Diels-Alder反応 : バレイショ夏疫病菌Alternaria solaniからの酵素の精製とその性質(口頭発表の部)

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First enzyme which catalyzes Diels-Alder reaction has been partially purified. This crude enzyme is able to catalyze [4+2]-cycloaddition of prosolanapyrone III to the exo adduct solanapyrone A and the endo adduct solanapyrone D in a 7:1 ratio differing substantially from the ratio found in a background reaction (exo/endo, 1:23). The optical purity of the enzymatic reaction product solanapyrone A was estimated as 92%ee by HPLC analysis monitored with CD spectrometer. The enzyme also exhibited an oxidase activity of prosolanapyrone II to III. Two-step conversion of prosolanapyrone II to solanapyrones A and B by the crude enzyme gave better diastereoselectivity and enantioselectivity (A: 99%ee). A high reaction rate of the background reaction for prosolanapyrone III caused some losses in both diastereo- and enantioselectivity. Thus, we suggest that a specific enzyme catalyzes both oxidation and Diels-Alder reaction producing enantiomerically pure solanapyrones.
天然有機化合物討論会の論文
1995-09-01