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Cinnamic acid 4-hydroxylase from cell cultures of the hornwort Anthoceros agrestis

Maike Petersen
Planta
Vol. 217, No. 1 (May 2003), pp. 96-101
Published by: Springer
Stable URL: http://www.jstor.org/stable/23387806
Page Count: 6
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Cinnamic acid 4-hydroxylase from cell cultures of the hornwort Anthoceros agrestis
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Abstract

Cinnamic acid 4-hydroxylase (EC 1.14.13.11), a cytochrome P450-dependent hydroxylase was for the first time characterized from a hornwort, Anthoceros agrestis Paton (Anthocerotaceae). In suspension cultures of A. agrestis up to 5% of the dry weight was accumulated as rosmarinic acid, a natural product commonly known from higher plants (e.g. species of the Lamiaceae and Boraginaceae). Cinnamic acid 4-hydroxylase is involved in the biosynthesis of rosmarinic acid. The participation of cytochrome P450 was demonstrated by the inhibition of hydroxylase activity by cytochrome c and the inhibition of cinnamic acid hydroxylation in a CO-containing atmosphere, which is partially released by illumination with blue light. The apparent Km values were determined to be at 60 μM and 5μM for NADPH and cinnamic acid, respectively. A comparatively high hydroxylation activity was seen with NADH as electron donor. While the hydroxylase activity with NADPH was strongly inhibited by the competitive electron acceptor cytochrome c, the activity with NADH was less susceptible, indicating the possibility of different electron-transfer pathways.

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