Crude particulate homogenates from leaves of barley (Hordeum vulgare L.), rice (Oryza sativa L.), leaf-beet (Beta vulgaris var. cicla L.) and pumpkin (Cucurbita pepo L.) cotyledons were separated on sucrose density gradients. The peroxisomal fractions appeared at a buoyant density of 1.25 g·cm-3 and contained most of the activities of catalase (EC 1.11.1.6), and hydroxypyruvate reductase (EC 1.1.1.81) on the gradients. In peroxisomal fractions from detached leaves and green cotyledons incubated in permanent darkness we detected the presence of isocitrate lyase (EC 4.1.3.1) and malate synthase (EC 4.1.3.2), key enzymes of the glyoxylate cycle, and β-oxidation activity (except in pumpkin). As proposed by H. Gut and P. Matile (1988, Planta 176, 548-550) the glyoxylate cycle may be functional during leaf senescence, and the presence of two key enzymes indicates a transition from leaf peroxisome to glyoxysome; for pumpkin cotyledons in particular a double transition occurs (glyoxysome to leaf peroxisome during greening, and leaf peroxisome to glyoxysome during senescence).

Localization of glyoxylate cycle marker enzymes in peroxisomes of senescent leaves and cotyledons

PICCIARELLI, PIERO;PISTELLI, LAURA;
1990

Abstract

Crude particulate homogenates from leaves of barley (Hordeum vulgare L.), rice (Oryza sativa L.), leaf-beet (Beta vulgaris var. cicla L.) and pumpkin (Cucurbita pepo L.) cotyledons were separated on sucrose density gradients. The peroxisomal fractions appeared at a buoyant density of 1.25 g·cm-3 and contained most of the activities of catalase (EC 1.11.1.6), and hydroxypyruvate reductase (EC 1.1.1.81) on the gradients. In peroxisomal fractions from detached leaves and green cotyledons incubated in permanent darkness we detected the presence of isocitrate lyase (EC 4.1.3.1) and malate synthase (EC 4.1.3.2), key enzymes of the glyoxylate cycle, and β-oxidation activity (except in pumpkin). As proposed by H. Gut and P. Matile (1988, Planta 176, 548-550) the glyoxylate cycle may be functional during leaf senescence, and the presence of two key enzymes indicates a transition from leaf peroxisome to glyoxysome; for pumpkin cotyledons in particular a double transition occurs (glyoxysome to leaf peroxisome during greening, and leaf peroxisome to glyoxysome during senescence).
De Bellis, L.; Picciarelli, Piero; Pistelli, Laura; Alpi, A:
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/14594
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 78
  • ???jsp.display-item.citation.isi??? 85
social impact