Pyruvate orthophosphate dikinase of C/sub 3/ seeds and leaves as compared to the enzyme from maize
Pyruvate orthophosphate dikinase (PPDK) was found in various immature seeds of C/sub 3/ plants (wheat, pea, green bean, plum, and castor bean), in some C/sub 3/ leaves (tobacco, spinach, sunflower, and wheat), and in C/sub 4/ (maize) kernels. The enzyme in the C/sub 3/ plants cross-reacts with rabbit antiserum against maize PPDK. Based on protein blot analysis, the apparent subunit size of PPDK from wheat seeds and leaves and from sunflower leaves is about 94 kdaltons, the same as that of the enzyme from maize, but is slightly less (about 90 kdaltons) for the enzyme from spinach and tobacco leaves. The amount of this enzyme per mg of soluble protein in C/sub 3/ seeds and leaves is much less than in C/sub 4/ leaves. PPDK is present in kernels of the C/sub 4/ plant, Zea mays in amounts comparable to those in C/sub 4/ leaves. Regulatory properties of the enzyme from C/sub 3/ tissues (wheat) are similar to those of the enzyme from C/sub 4/ leaves with respect to in vivo light activation and dark inactivation (in leaves) and in vitro cold lability (seeds and leaves). Following incorporation of /sup 14/CO/sub 2/ by illuminated wheat pericarp and adjoining tissue for a few seconds, the labeled metabolites were predominantly products resulting from carboxylation of phospheonolpyruvate, with lesser labeling of compounds formed by carboxylation of ribulose 1,5-bisphosphate and operation of the reductive pentose phosphate cycle of photosynthesis. PPDK may be involved in mechanisms of amino acid interconversions during seed development. 13 references, 5 figures, 1 tables.
- Research Organization:
- Lawrence Berkeley Lab., CA
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6137399
- Journal Information:
- Plant Physiol.; (United States), Vol. 75:2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOTRANSFERASES
ENZYME ACTIVITY
PLANT TISSUES
METABOLISM
AMINO ACIDS
CARBON 14 COMPOUNDS
CASTOR
COMPARATIVE EVALUATIONS
LEAVES
MAIZE
METABOLITES
NICOTIANA
PHASEOLUS
PHOTOSYNTHESIS
PISUM
PLUMS
PROTEINS
SEEDS
SPINACH
SUNFLOWERS
TRACER TECHNIQUES
WHEAT
BODY
CARBOXYLIC ACIDS
CEREALS
CHEMICAL REACTIONS
ENZYMES
FOOD
FRUITS
GRASS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEGUMINOSAE
MEDICINAL PLANTS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
PHOTOCHEMICAL REACTIONS
PLANTS
SYNTHESIS
TISSUES
TRANSFERASES
VEGETABLES
550201* - Biochemistry- Tracer Techniques