A Parallel Study of Pigment Bleaching and Cytochrome Breakdown during Aging of Thylakoid Membranes

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概要

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• Aging of freshly isolated thylakoid membranes from spinach leaves (Spinacia oleracea L.) leads to dramatic alterations in both the cytochrome (b_<559(HP)> and f) composition and pigment (chlorophylls a and b and β-carotene) content. These changes occur at a faster rate under anaerobic conditions or after heating thylakoid membranes, and in light as well as in darkness. In addition, when thylakoid membranes are heated at 78℃ for 8 min, or incubated in the presence of an emulsion of linoleic acid, a huge decrease in both cytochrome (particularly cyt. b_<559(HP)>) and pigment contents occur. Whatever the experimental conditions, cytochrome b_<559(HP)> destruction occurs as soon the aging process starts. Conversely, pigment bleaching is detectable after an initial lag phase of about 60-70 min. Then, the two processes (cytochrome breakdown and bleaching of pigments) appear to take place in parallel. The addition of salicylhydroxamic acid or 8-hydroxy-quinoline, two radical scavenger components, to the aging medium strongly reduces the rate and extent of cytochrome breakdown and pigment bleaching. On the basis of these results, a tentative scheme accounting for the bleaching of pigments and the breakdown of cytochromes during aging in vitro of thylakoid membranes is proposed. It is suggested that these changes are mediated via a non-enzymatic mechanism in which free radicals could be implicated. The possible role of free radicals inducing ultrastructural changes at the level of chloroplast membranes in senescent leaves is also considered.

• 日本植物生理学会の論文

著者

• Siegenthaler P‐a

  Univ. Neuchatel Neuchatel Che

• Siegenthaler Paul-Andre

  Laboratoire de Physiologie vegetale, Universite de Neuchatel

• Dupont Jacques

  Laboratoire de Biologie Vegetale IV,. CNRS (UA 1180), Universite Pierre et Marie Curie

• Dupont J

  Univ. Pierre Et Marie Curie Paris Fra

• Siegenthaler Paul-andre

  Laboratoire De Physiologie Vegetable Et Biochimie Universite

関連論文

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