Effects of glycerol on the in vitro stability and regulatory activation/inactivation of pyruvate, orthophosphate dikinase ofZea maysL.
✍ Scribed by G. Salahas; Y. Manetas; N. A. Gavalas
- Publisher
- Springer
- Year
- 1990
- Tongue
- English
- Weight
- 541 KB
- Volume
- 26
- Category
- Article
- ISSN
- 0166-8595
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✦ Synopsis
Glycerol stabilizes the activity of pyruvate, orthophosphate dikinase extracted from darkened or illuminated maize leaves. It serves as a better protectant of activity than dithiothreitol for the active day-form and the glycerol concentration needed for full protection is inversely related to the level of protein. The night-form of the enzyme is also protected by glycerol not only against inactivation, but also against partial reactivation in storage. Glycerol does not prevent the Pi-dependent activation nor the ADP-dependent inactivation of pyruvate, orthophosphate dikinase, but the rates of both processes are substantially decreased. The ability of the inactive night-form for Pi-dependent activation is also sustained by glycerol for at least 2 h at 20°C, apparently through stabilization of the labile regulatory protein.