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Detection of 1-aminocyclopropane-1-carboxylate oxidase activity in seeds of Stylosanthes humilis H.B.K

R. Barros,Frank James Araújo Pinheiro,C. Müller,M. Pires,Alexei Gresta Vieira da Silva,D. Ribeiro

Published 2013 in Theoretical and Experimental Plant Physiology

ABSTRACT

The activity of 1-aminocyclopropane-1-carboxylate oxidase (ACO) was characterized in seeds of the tropical legume Townsville stylo (Stylosanthes humilis) both in vitro (desalted extract of non-dormant seeds) and in vivo (entire dormant seeds). Optimum conditions for maximum in vitro ACO activity in a Trizma-HCl 100 mM buffered medium were: pH 7.0, temperature 32oC and cofactors and co-substrate at the following concentrations: NaHCO3 30 mM, sodium ascorbate 30 mM and FeSO4 50 µM. Rates of in vitro reaction catalyzed by ACO were shown to be constant within the interval 15-150 minutes from the onset of the reaction. The apparent Km for in vitro ACO, as determined from the non-linear curve fitting to the Michaelis-Menten equation, was 156±8.3 µM ACC with a Vmax 5.4±0.08 mmol (ET) g-1 h-1 on a fresh matter (FM) basis. In vivo (control basal medium: HCl-KOH 10 mM pH 7.0, 30oC, reaction time 15 hours) apparent Km was 230±27 µM ACC and Vmax 11.9±0.38 mmol (ET) g-1.h-1 on a FM basis. These data suggest that the enzyme exhibits a relatively low affinity for the substrate. The well-known inhibitors of ACO activity, α-aminoisobutyric acid, salicylic and acetylsalicylic acids, n-propylgallate and cobaltous ions, were highly effective in inhibiting ACO activity of Townsville stylo seeds.

PUBLICATION RECORD

  • Publication year

    2013

  • Venue

    Theoretical and Experimental Plant Physiology

  • Publication date

    Unknown publication date

  • Fields of study

    Biology, Chemistry, Environmental Science

  • Identifiers
    DOI 10.1590/S2197-00252013000300008
  • External record

    Open on Semantic Scholar

  • Source metadata

    Semantic Scholar

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