An Enzyme Extract from Douglas-Fir Sapwood and Its Relationship To Brown Staining


  • Murray L. Laver
  • Durria Abdel Azim Musbah


Polyphenol oxidase, Douglas-fir sapwood, chemical stains, brown stains, protein extraction, enzyme activity


A chemical or enzymatic brown stain in sapwood of Douglas-fir has caused financial losses to lumber producers, particularly those producing valuable clear grades of export lumber. This work shows that the brown stain may be caused, at least in part, by an enzyme system in the sapwood. Buffered extracts of Douglas-fir sapwood showed enzyme activity when added to solutions containing o-diphenol and polyphenol compounds. No activity for monophenol substrates was detected. The enzymatic extract showed two pH optima for activity, one at pH 5.5 and one at pH 8.0, with the activity at pH 8.0 being somewhat greater. The activity was also temperature-dependent, with the highest activity at 35°. The extract showed highest activities with the compounds (—)-epicatechin, dihydroquercetin, and 4-methylcatechol.


Arvey, S. W. 1993. Chemical brown stain of Douglasfir wood. Ph.D. thesis, Oregon State University, Corvallis, OR.nBio-Rad. 1989. Bio-Rad protein assay. Bio-Rad technical literature. Richmond, CA.nFlurkey, W. H., and J. J. Jen. 1978. Peroxidase and polyphenol oxidase activities in developing peaches. J. Food Sci. 43:1826-1828.nGomori, G. 1955. Preparation of buffers for use in enzyme studies. Pages 138-146 in S. P. Colowick and N. O. Kaplan, eds. Methods in enzymology, vol. 1. Academic Press, New York, NY.nGuttridge, S., and D. A. Robb. 1975. Catecholase activity of Neurospora tyrosinase. Eur. J. Biochem. 54: 107-116.nInteresse, F. S., P. Ruggiero, G. D'avella, and F. Lamparelli. 1980. Partial purification of some properties of wheat (Triticum aestivum) o-diphenolase. J. Sci. Food Agric. 31:459-466.nJolley, R. L., L. H. Evans, N. Makino, and H. S. Mason. 1974. Oxytyrosinase. J. Biol. Chem. 249(2):335-345.nMayer, A.M., and E. Harel. 1979. Review: Polyphenol oxidases in plants. Phytochem. 18:193-215.nMiller, D. J., D. M. Knutson, and R. D. Tocher. 1983. Chemical brown staining of Douglas-fir sapwood. Forest Prod. J. 33(4):44-48.nOta, M., S. Onodera, M. Ohira, and K. Taneda. 1991. The chemistry of color changes in Kiri wood (Paulownia tomentosa Steud.) II. Radial distributions and seasonal variations of the contents of total phenolics, of caffeic acid sugar esters, and of kiri peroxidase activity in the xylem, plus some properties of kiri peroxidase. Mokuzai Gakkaishi 37(3):254-260.nSong, H.-K. 1988. Chemistry of phenolic stains in Douglas-fir sapwood. Ph.D. thesis, Oregon State University, Corvallis, OR.nSpector, T. 1979. Refinement of the Coomassie Blue method of protein quantification. Anal. Biochem. 86: 142-146.nWissemann, K. W., and C. Y. Lee. 1981. Characterization of polyphenoloxidase from Ravat 51 and Niagara grapes. J. Food Sci. 46:506-508, 514.n






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