Stereospecificity of (+)-pinoresinol and (+)-lariciresinol reductases from Forsythia intermedia

Alex Chu, Albena Dinkova, Laurence B. Davin, Diana L. Bedgar, Norman G. Lewis

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Pinoresinol/lariciresinol reductase catalyzes the first known example of a highly unusual benzylic ether reduction in plants; its mechanism of hydride transfer is described. The enzyme was found in Forsythia intermedia and catalyzes the presumed regulatory branch-points in the pathway leading to benzylaryltetrahydrofuran, dibenzylbutane, dibenzylbutyrolactone, and aryltetrahydronaphthalene lignans. Using [7,7′-2H2]-pinoresinol and [7,7′-2H3]lariciresinol as substrates, the hydride transfers of the highly unusual reductase were demonstrated to be completely stereospecific (>99%). The incoming hydrides were found to take up the pro-R position at C-7′ (and/or C-7) in lariciresinol and secoisolariciresinol, thereby eliminating the possibility of random hydride delivery to a planar quinone methide intermediate. As might be expected, the mode of hydride abstraction from NADPH was also stereospecific: using [4A-3H] and [4S-3H]NADPH, it was found that only the 4 pro-R hydrogen was abstracted for enzymatic hydride transfer.

Original languageEnglish
Pages (from-to)27026-27033
Number of pages8
JournalJournal of Biological Chemistry
Volume268
Issue number36
Publication statusPublished - 25 Dec 1993

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