VIEW ARTICLE

Physiology and Biochemistry

In Vitro Protein Polymerization by Quinones or Free Radicals Generated by Plant or Fungal Oxidative Enzymes. Gary F. Leatham, Research assistant, Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison 53706, Present address of senior author: USDA-Forest Service, P.O. Box 5130, Madison, Wisconsin 53705; V. King(2), and Mark A. Stahmann(3). (2)(3)Student, and professor, respectively, Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison 53706. Phytopathology 70:1134-1140. Accepted for publication 6 April 1980. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-1134.

A model system of horseradish peroxidase, mushroom polyphenol oxidase, or sodium periodate and a phenolic compound was found to polymerize and precipitate soluble proteins. Polyacrylamide SDS gel electrophoresis revealed the presence of protein dimers, trimers, and higher polymers that formed by protein reaction with quinones or free radicals. Physiological concentrations of widespread naturally occurring phenolics, hydroxycoumarins, and flavonoids were capable of participating in the crosslinking reaction. The conditions under which the crosslinking reaction occurred were studied, and its possible mechanism and biological significance is discussed.