Characteristics of ribulose-1,5-bisphosphate carboxylase/oxygenase degradation by lysates of mechanically isolated chloroplasts from wheat leaves

Kenji Miyadai, Tadahiko Mae, Amane Makino, Kunihiko Ojima

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The lysate from intact chloroplasts mechanically isolated from primary leaves of 9 day old seedlings of wheat (Triticum aestivum L. var Aoba) was incubated in the pH range of 5.5 to 8.5 at 37°C for 5 hours. Proteolytic activity against ribulose-1.5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) was estimated by disappearance of the large subunit of Rubisco or the appearance of its degradation products. Although the activity in lysates was weak, the products were detected by applying Western blotting. The degradation products were similar to those obtained when Rubisco was incubated with the lysate of vacuoles isolated from like leaves. Although some of the products were similar to those from vacuole lysates, many were clearly different after incubation of Rubisco with trypsin, V-8 protease, or reactive oxygen (hydroxy radical). Lysates of chloroplasts, pretreated with thermolysin at 4°C for 30 minutes, had no proteolytic activity against Rubisco after incubation at 37°C for 5 hours. These results show that the proteolytic activity against Rubisco found in lysates of our mechanically isolated chloroplasts was mostly due to the contamination of vacuolar proteases adhering to the outer envelope of the chloroplasts during their isolation.

Original languageEnglish
Pages (from-to)1215-1219
Number of pages5
JournalPlant physiology
Volume92
Issue number4
DOIs
Publication statusPublished - 1990 Apr

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

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