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United States Department of Agriculture

Agricultural Research Service

Title: Formation of Dehydrodiferules by Peroxidases

Authors
item Hatfield, Ronald
item Jones, Beth - UNIV OF WISCONSIN
item Grabber, John
item Ralph, John

Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: August 29, 1995
Publication Date: N/A

Technical Abstract: Cell wall peroxidases of maize cultures and other grasses form a range of ferulate dehydrodimers in addition to the typically reported 5-5 diferulate. This work was undertaken to determine if unique peroxidases were responsible for the formation of dehydrodimers. Peroxidases were isolated from walls or media of 14-18 day old cultures (Zea mays, cv. Black kMexican) and fractionated into PI groups by conventional liquid chromatography and isoelectric focusing techniques. Three major groups were separated (acidic PI 4-5.5; neutral PI 6-7.5; and basic PI 8.5-9), and activities against several phenolic substrates were tested revealing kinetic differences. Of major interest were ferulate substrates and the resulting dehydrodiferulates produced. For all peroxidases tested, products identified arose from oxidative coupling to produce 8-5; 8-8; and 8-O-4 dehydrodiferulates. No 5-5 dehydrodiferulate was detected in the reaction mixture for any of the peroxidase groups. The 5-5 coupled ferulat may not be a preferred free radical coupling product, and its formation within the wall may be the result of steric restrictions as opposed to enzyme specificity.

Last Modified: 12/22/2014
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