Purification and characterization of a wound-inducible cell wall cationic peroxidase from carrot roots.
We have isolated a novel cell wall, cationic peroxidase (pI > 9.3) from roots of the carrot plant, Daucus carota. The purified isozyme, referred to as CP > 9.3, has a molecular mass of 45 kilodaltons and an Reinheitzahl value of 2.3. Amino-acid composition analysis and N-terminal sequencing have been performed with CP > 9.3. The N-terminal sequence shows no homology to any sequence in the protein and nucleic acid data banks. CP > 9.3 activity is induced by wounding in carrot leaves and petioles; this activity is also present in carrot roots but is unaltered by wounding. Enhanced CP > 9.3 activity is seen at 12 hr post-wounding and continues for at least 60 hr in leaves and petioles. Based on studies using cycloheximide, early activation of CP > 9.3 is not due to de novo protein synthesis, but rather to enzyme activation. Temperature and pH optima for CP > 9.3 using guaiacol as a substrate have been determined to be 32 degrees C and 4.9.
Nair
A R
AR
Department of Environmental and Plant Biology, Ohio University, Athens 45701-2979, USA.
Showalter
A M
AM
D000595:Amino Acid Sequence; D002473:Cell Wall / Q000201:enzymology; D002852:Chromatography, Ion Exchange; D018552:Daucus carota / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D004790:Enzyme Induction; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010544:Peroxidases / Q000096:biosynthesis / Q000302:isolation & purification* / Q000378:metabolism
D010544:Peroxidases