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Cytokinin oxidase from wheat: partial purification and general properties
Plant Physiology
|July 1, 1989
Summary
Researchers identified and partially purified a novel cytokinin oxidase enzyme from wheat germ. This enzyme efficiently degrades specific cytokinin forms, suggesting a role in plant hormone regulation.
Area of Science:
- Plant Biochemistry
- Enzymology
- Hormone Metabolism
Background:
- Cytokinin-binding protein 1 (CBF-1) is abundant in wheat embryos.
- Understanding cytokinin metabolism is crucial for plant growth and development.
Purpose of the Study:
- To investigate the potential role of CBF-1 by identifying associated enzymes.
- To characterize a novel cytokinin oxidase from wheat (Triticum aestivum L.) germ.
Main Methods:
- Partial purification of cytokinin oxidase using conventional techniques and high-performance chromatofocusing.
- Enzyme kinetics determined via Vmax and Km measurements.
- Enzyme properties assessed using high-performance gel permeation chromatography.
Main Results:
- A cytokinin oxidase was purified from wheat germ, showing high affinity (Km = 0.3 µM) for N(6)-(Delta(2)-isopentenyl)adenosine.
- The enzyme has an apparent molecular weight of 40,000 Da and requires oxygen.
- Substrate specificity includes N(6)-(Delta(2)-isopentenyl)adenine and zeatin riboside, but not the 5'-monophosphate.
- Benzyladenine is a weak substrate and inhibitor; diphenylurea derivatives strongly inhibit activity.
Conclusions:
- The characterized wheat germ cytokinin oxidase is distinct from previously reported enzymes.
- This enzyme likely plays a significant role in regulating cytokinin levels in wheat.
- Inhibitor studies suggest potential applications in controlling plant hormone activity.
