Glyoxysomal malate dehydrogenase of watermelon cotyledons: De novo synthesis on cytoplasmic ribosomes

R. A. Walk, B. Hock

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39 Scopus citations

Abstract

The development of glyoxysomal malate dehydrogenase (gMDH, EC 1.1.1.37) during early germination of watermelon seedlings (Citrullus vulgaris Schrad.) was determined in the cotyledons by means of radial immunodiffusion. The active isoenzyme was found to be absent in dry seeds. By density labelling with deuterium oxide and incorporation of [14C] amino acids it was shown that the marked increase of gMDH activity in the cotyledons during the first 4 days of germination was due to de novo synthesis of the isoenzyme. The effects of protein synthesis inhibitors (cycloheximide and chloramphenicol) on the synthesis of gMDH indicated that the glyoxysomal isoenzyme was synthesized on cytoplasmic ribosomes. Possible mechanisms by which the glyoxysomal malate dehydrogenase isoenzyme reaches its final location in the cell are discussed.

Original languageEnglish
Pages (from-to)277-285
Number of pages9
JournalPlanta
Volume134
Issue number3
DOIs
StatePublished - Jan 1977
Externally publishedYes

Keywords

  • Citrullus
  • Enzyme synthesis
  • Glyoxysomes
  • Malate dehydrogenase
  • Seed germination

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