title: Nitric oxide increases the enzymatic activity of three ascorbate peroxidase isoforms in soybean root nodules.
abstract: Ascorbate peroxidase is one of the major enzymes regulating the levels of H2O2 in plants and plays a crucial role in maintaining root nodule redox status. We used fully developed and mature nitrogen fixing root nodules from soybean plants to analyze the effect of exogenously applied nitric oxide, generated from the nitric oxide donor 2,2'-(hydroxynitrosohydrazono)bis-ethanimine, on the enzymatic activity of soybean root nodule ascorbate peroxidase. Nitric oxide caused an increase in the total enzymatic activity of ascorbate peroxidase. The nitric oxide-induced changes in ascorbate peroxidase enzymatic activity were coupled to altered nodule H2O2 content. Further analysis of ascorbate peroxidase enzymatic activity identified three ascorbate peroxidase isoforms for which augmented enzymatic activity occurred in response to nitric oxide. Our results demonstrate that nitric oxide regulates soybean root nodule ascorbate peroxidase activity. We propose a role of nitric oxide in regulating ascorbate-dependent redox status in soybean root nodule tissue.
authors.affiliation: Department of Biotechnology, University of the Western Cape, Bellville, South Africa.
authors.forename: Marshall
authors.initials: M
authors.lastname: Keyster
authors.forename: Ashwil
authors.initials: A
authors.lastname: Klein
authors.forename: Ifeanyi
authors.initials: I
authors.lastname: Egbichi
authors.forename: Alex
authors.initials: A
authors.lastname: Jacobs
authors.forename: Ndiko
authors.initials: N
authors.lastname: Ludidi
mesh_terms: D060387:Ascorbate Peroxidases / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D020033:Protein Isoforms / Q000378:metabolism*; D053204:Root Nodules, Plant / Q000187:drug effects* / Q000201:enzymology*; D013025:Glycine max / Q000187:drug effects* / Q000201:enzymology*
chemical_list: D020030:Nitric Oxide Donors; D020033:Protein Isoforms; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases