Induction of an anionic peroxidase in cowpea leaves by exogenous salicylic acid.
Two isoperoxidases were detected in cowpea (Vigna unguiculata) leaves. Treatment of the primary leaves with 10mM salicylic acid increased the total peroxidase activity contributed by the anionic isoform. To isolate both the anionic and cationic peroxidases the leaf crude extract was loaded on a Superose 12 HR 10/30 column followed by chromatography on Mono-Q HR 5/5. Both enzymes were stable in a pH range from 5 to 7. The optimum-temperatures for the cationic and anionic peroxidase isoforms were, respectively, 20-30 degrees C and 30 degrees C. The dependence of guaiacol oxidation rate varying its concentration at constant H(2)O(2) concentration showed, for both enzymes, Michaelis-Menten-type kinetic. Apparent K(m)(s) were 0.8 and 4.8 microM for the cationic and anionic isoperoxidases, respectively.
Fernandes
Cléberson F
CF
Embrapa Rondônia, Porto Velho, Rondônia, Brazil.
Moraes
Vadjah C P
VC
Vasconcelos
Ilka M
IM
Silveira
Joaquim A G
JA
Oliveira
José T A
JT
D002845:Chromatography / Q000379:methods; D004790:Enzyme Induction; D007887:Fabaceae / Q000187:drug effects / Q000201:enzymology*; D006139:Guaiacol / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D009195:Peroxidase / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D018515:Plant Leaves / Q000201:enzymology; D020156:Salicylic Acid / Q000494:pharmacology*
D007527:Isoenzymes; D006139:Guaiacol; D009195:Peroxidase; D020156:Salicylic Acid