บทคัดย่องานวิจัย

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Isoforms of glutamine synthetase in asparagus spears: the cytosolic enzyme increases after harvest.

Downs, C. G.; Borst, W. M.; Hurst, P. L.; Stevenson, D. G.;

Plant, Cell and Environment Year: 1994 Vol: 17 Issue: 9 Pages: 1045-1052 Ref: 40 ref.

1994

บทคัดย่อ

Isoforms of glutamine synthetase in asparagus spears: the cytosolic enzyme increases after harvest.

ABSTRACT :

 

Two distinct forms of glutamine synthetase (GS) [glutamate-ammonia ligase] were identified in the spear tip tissues of harvested Asparagus cv. Limbras 10. The GS activities were separated by anion exchange chromatography. They had distinct kinetic properties and contained polypeptides of different sizes, and the abundances of the GS isoforms changed differently after harvest. Plastid GS had a 44-kDa polypeptide, and during the postharvest period (storage in darkness at 20 deg C for up to 5 days) the abundance of this polypeptide declined dramatically. After 5 days, the activity of plastid GS had declined to just 20% of that at harvest. Cytosolic GS had a 40-kDa polypeptide and was the major constituent of the GS activity present at harvest (73% of total). After harvest, cytosolic GS activity declined by half and then, at 3 or 4 days after harvest, rose to 80% of the cytosolic GS activity present at harvest. The nitrogen metabolism of Asparagus spears was significantly altered as the tissues dete

riorated rapidly after harvest. It was demonstrated that cytosolic GS activity increased during the postharvest period and is likely to be a critical feature of the physiology of the tip of a harvested Asparagus spear.