E. Aboutabl, A. Azzouny, K. Winter
1976
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0
Influential Citations
14
Citations
Journal
Phytochemistry
Abstract
Abstract Cyclopeptine dehydrogenase, an enzyme from Penicillium cyclopium , catalyses the reversible transformation of the benzodiazepine alkaloids cyclopeptine and dehydrocyclopeptine. By the dehydrogenation of cyclopeptine two hydrogen atoms are removed from the positions 3 and 10. It was demonstrated that, from the two optical isomers of cyclopeptine, only the naturally occurring 3 S -compound was used as substrate by cyclopeptine dehydrogenase. To test the stereospecificity of the enzyme with respect to the second hydrogen which is eliminated from C-10 a mixture of cyclopeptine-3 S -[10 R - 3 H 1 ] and cyclopeptine-3 R -10 S - 3 H 1 ] was prepared. The 3 S -isomer was transformed by the enzyme into radioactively labelled dehydrocyclopeptine. This demonstrated that cyclopeptine dehydrogenase removes the 10-pro S hydrogen atom from the cyclopeptine molecule. Because the formed dehydrocyclopeptine has the trans -configuration it is probable that a synperiplanar elimination takes place. The hydride ion removed from cyclopeptine is transferred to the 4-pro R -position of NAD + . Cyclopeptine dehydrogenase thus belongs to the A-specific dehydrogenases.