Inhibition of electron transport activities in mitochondria from avocado and pepper fruit by naturally occurring polyamines |
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Authors: | Donna C Phelps Roy E McDonald |
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Institution: | US Dept of Agriculture, ARS, 2120 Camden Road, Orlando, FL 32803. USA. |
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Abstract: | The effects of the naturally occurring polyamines, spermine, putrescine, and spermidine were explored on mitochondrial state 3. state 4, and uncoupled respiration activities, ADP/O ratio, respiratory control ratio of pepper ( Capsicum annuum L. cv. Early Cal Wonder) and avocado ( Persea americana Mill. cv. Booth-8 or Simmonds) mitochondria oxidizing either succinate, external NADH, malate, α-ketoglutarate or tetramethyl- p -phenylenediamine. Abnormally high concentrations of spermine and spermidine such as might occur during chilling stress of these chilling-sensitive fruits were detrimental to several oxidase activities, especially to external NADH oxidase. State 3 respiration for NADH oxidase was inhibited more than 70% by 10 m M spermine. The spermine inhibition of uncoupled NADH oxidase was not reversed by the presence of divalent cations including Ca2+, Mg2+, Mn2+, and Sr2+ at concentrations up to 10 m M or by 100 m M KCl. The inhibition primarily affected the Vmax. Other possible sites of polyamine interactions are discussed. |
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Keywords: | Avocado Capsicum annuum chilling injury mitochondria pepper Persea americana polyamine putrescine spermidine spermine |
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