title: Beyond brown: polyphenol oxidases as enzymes of plant specialized metabolism.
abstract: Most cloned and/or characterized plant polyphenol oxidases (PPOs) have catechol oxidase activity (i.e., they oxidize o-diphenols to o-quinones) and are localized or predicted to be localized to plastids. As a class, they have broad substrate specificity and are associated with browning of produce and other plant materials. Because PPOs are often induced by wounding or pathogen attack, they are most generally believed to play important roles in plant defense responses. However, a few well-characterized PPOs appear to have very specific roles in the biosynthesis of specialized metabolites via both tyrosinase (monophenol oxidase) and catechol oxidase activities. Here we detail a few examples of these and explore the possibility that there may be many more "biosynthetic" PPOs.
authors: U.S. Dairy Forage Research Center, Agricultural Research Service, United States Department of Agriculture Madison, WI, USA.
authors: Michael L
authors: ML
authors: Sullivan
keywords: 8-8’ linked lignans; L-DOPA; aurones; betalains; metabolism; specialized metabolism; tyramine; tyrosine
references: Biochem J. 1969 Jun;113(1):109-15
references: 4389984
references: J Exp Bot. 2010 Jul;61(12 ):3451-9
references: 20566567
references: Crit Rev Food Sci Nutr. 1981;15(1):49-127
references: 6794984
references: Science. 2000 Nov 10;290(5494):1163-6
references: 11073455
references: Plant Sci. 2001 Jan 5;160(2):229-236
references: 11164594
references: J Agric Food Chem. 1999 Jul;47(7):2571-8
references: 10552528
references: Nat Genet. 2012 Jun 03;44(7):816-20
references: 22660548
references: J Chem Ecol. 1985 Jan;11(1):27-33
references: 24311094
references: Planta. 2011 Mar;233(3):439-70
references: 21063888
references: BMC Genomics. 2012 Aug 16;13:395
references: 22897796
references: Plant J. 2006 Jan;45(2):133-43
references: 16367960
references: Plant J. 2002 Apr;30(1):33-45
references: 11967091
references: J Agric Food Chem. 2010 Oct 13;58(19):10597-605
references: 20853835
references: FEBS Lett. 2014 Sep 17;588(18):3417-26
references: 25109778
references: Trends Plant Sci. 2013 Jun;18(6):334-43
references: 23395307
references: Anticancer Drug Des. 2001 Dec;16(6):261-70
references: 12375879
references: Sci Rep. 2013;3:1970
references: 23760173
references: Phytochemistry. 2006 Nov;67(21):2318-31
references: 16973188
references: Trends Plant Sci. 2003 Jun;8(6):263-71
references: 12818660
references: Proc Natl Acad Sci U S A. 2003 Sep 16;100(19):10641-6
references: 12960376
references: Plant Physiol. 2014 Mar;164(3):1191-203
references: 24449710
references: FEBS Lett. 2001 Jun 15;499(1-2):107-11
references: 11418122
references: Proc Natl Acad Sci U S A. 2006 Jul 18;103(29):11075-80
references: 16832053
references: J Biol Chem. 2001 Sep 28;276(39):36566-74
references: 11429408
references: Phytochemistry. 2002 Jul;60(6):551-65
references: 12126701
references: Antiviral Res. 2000 Jul;47(1):19-28
references: 10930643
references: Planta. 2004 Nov;220(1):105-17
references: 15300439
references: Front Plant Sci. 2014 Dec 10;5:689
references: 25540647