TY - JOUR
T1 - Catabolism of indole‐3‐acetic acid in citrus leaves
T2 - identification and characterization of indole‐3‐aldehyde oxidase
AU - Winer, Leo
AU - Riov, Joseph
AU - Goren, Raphael
PY - 1993/9
Y1 - 1993/9
N2 - A new enzyme, named indole‐3‐aldehyde oxidase (IAldO), was identified in citrus (Citrus sinensis L. Osbeck cv. Shamouti) leaves. The enzyme was partially purified by (NH4)2SO4 fractionation. Sephadex G‐200 gel filtration and DEAE‐cellulose ion exchange chromatography. IAldO catalyzes the oxidation of indole‐3‐aldehyde (IAld) to indole‐3‐carboxylic acid (ICA) with the production of H2O2. The enzyme is highly specific for IAld. The apparent KM of the enzyme for IAld is 19 μM. The optimum oxidation of IAld occurs at pH 7. 5. The molecular mass of the enzyme, as determined by Sepharose‐6B gel filtration, is about 200 kDa. Based on inhibitor studies, it is concluded that IAldO is not a flavin‐linked oxidase and there is no requirement for free sulfhydryl groups or divalent cations for maximum activity. The enzyme is strongly inhibited by benzaldehyde. Ethylene pretreatment, wounding and aging of leaf tissues did not affect enzyme activity, suggesting that the enzyme is constitutive in citrus tissues.
AB - A new enzyme, named indole‐3‐aldehyde oxidase (IAldO), was identified in citrus (Citrus sinensis L. Osbeck cv. Shamouti) leaves. The enzyme was partially purified by (NH4)2SO4 fractionation. Sephadex G‐200 gel filtration and DEAE‐cellulose ion exchange chromatography. IAldO catalyzes the oxidation of indole‐3‐aldehyde (IAld) to indole‐3‐carboxylic acid (ICA) with the production of H2O2. The enzyme is highly specific for IAld. The apparent KM of the enzyme for IAld is 19 μM. The optimum oxidation of IAld occurs at pH 7. 5. The molecular mass of the enzyme, as determined by Sepharose‐6B gel filtration, is about 200 kDa. Based on inhibitor studies, it is concluded that IAldO is not a flavin‐linked oxidase and there is no requirement for free sulfhydryl groups or divalent cations for maximum activity. The enzyme is strongly inhibited by benzaldehyde. Ethylene pretreatment, wounding and aging of leaf tissues did not affect enzyme activity, suggesting that the enzyme is constitutive in citrus tissues.
KW - Citrus sinensis
KW - IAA
KW - IAA catabolism
KW - indole‐3‐aldehyde
KW - indole‐3‐carboxylic acid
UR - http://www.scopus.com/inward/record.url?scp=84989695150&partnerID=8YFLogxK
U2 - 10.1111/j.1399-3054.1993.tb01809.x
DO - 10.1111/j.1399-3054.1993.tb01809.x
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AN - SCOPUS:84989695150
SN - 0031-9317
VL - 89
SP - 220
EP - 226
JO - Physiologia Plantarum
JF - Physiologia Plantarum
IS - 1
ER -