Articles
THE ENZYMATICAL FORMATION OF A DIMERIC PRODUCT OF FERULIC ACID FROM THE MICROSOMAL FRACTION OF ZEA MAYSL.
Article number
381_4
Pages
81 – 85
Language
Abstract
The microsomal fraction of etiolated seeds of Zea mays L. is able to metabolise phenylpropanoid acids with hydroxyl substituents in p-position.
Based upon experimental results the participation of a peroxidase could be made probable.
That is indicated by a strong inhibition of the enzymatic reaction by cyanide ions and catalase.
A potential cosubstrate of this reaction is H2O2. The substrate used was ferulic acid.
In the native plant the H2O2-generating system exists, which produces H2O2 from NAD(P)H and O2 (Gross et al., 1977) as well as leading to the in vitro provision of the cosubstrate.
In comparison to NADPH in the test-tube the use of H2O2 leads to a 26.4 fold increase of the product formation.
The resulting product could be eluated by HPLC (RP-18 column). In contrast to the substrate ferulic acid (R1=22,5 min) the product is characterized by higher polarity (R1=8,5 min). The IR-spectrum shows an unchanged circular structure at a wave number of 1598 cm-1. In the UV-spectrum a bathochrome shifting of the maxima from substrate (234/321 nm) to the product (234/334 nm) is observed.
The mass spectrum of ESMS (Electrospray Mass Spectrometry) shows a mass number (m/z) of 408.9, which after subtraction of a Nation has a m/z of 386 for the organic product.
The EIMS (Electron Impact Mass Spectrometry) agrees with the ESMS, since the molecular ion appears at m/z of 386. The results until now indicate the synthesis of a 8,8′-bis-ferulic acid [8,8′-bis-(4-hydroxy-3-methoxy-phenylpropen acid)].
Based upon experimental results the participation of a peroxidase could be made probable.
That is indicated by a strong inhibition of the enzymatic reaction by cyanide ions and catalase.
A potential cosubstrate of this reaction is H2O2. The substrate used was ferulic acid.
In the native plant the H2O2-generating system exists, which produces H2O2 from NAD(P)H and O2 (Gross et al., 1977) as well as leading to the in vitro provision of the cosubstrate.
In comparison to NADPH in the test-tube the use of H2O2 leads to a 26.4 fold increase of the product formation.
The resulting product could be eluated by HPLC (RP-18 column). In contrast to the substrate ferulic acid (R1=22,5 min) the product is characterized by higher polarity (R1=8,5 min). The IR-spectrum shows an unchanged circular structure at a wave number of 1598 cm-1. In the UV-spectrum a bathochrome shifting of the maxima from substrate (234/321 nm) to the product (234/334 nm) is observed.
The mass spectrum of ESMS (Electrospray Mass Spectrometry) shows a mass number (m/z) of 408.9, which after subtraction of a Nation has a m/z of 386 for the organic product.
The EIMS (Electron Impact Mass Spectrometry) agrees with the ESMS, since the molecular ion appears at m/z of 386. The results until now indicate the synthesis of a 8,8′-bis-ferulic acid [8,8′-bis-(4-hydroxy-3-methoxy-phenylpropen acid)].
Authors
W. Gröger, H. Förster, U. Pommer
Keywords
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