| Abstrakt: |
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 mM 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 mM or by 100 mM KCl. The inhibition primarily affected the Vmax Other possible sites of polyamine interactions are discussed. [ABSTRACT FROM AUTHOR] |
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