Amino acid synthesis in photosynthesizing spinach cells: effects of ammonia on pool sizes and rates of labeling from /sup 14/CO/sub 2/

Journal Article · Thu Jan 01 04:00:00 EST 1981 · Plant Physiol.; (United States)

OSTI ID:6570455

Larsen, P O; Cornwell, K L; Gee, S L; Bassham, J A

Isolated cells from leaves of Spinacia oleracea have been maintained in a state capable of high rates of photosynthetic CO/sub 2/ fixation for more than 60 hours. The incorporation of /sup 14/CO/sub 2/ under saturating CO/sub 2/ conditions into carbohydrates, carboxylic acids, and amino acids, and the effect of ammonia on this incorporation have been studied. Total incorporation, specific radioactivity, and pool size have been determined as a function of time for most of the protein amino acids and for ..gamma..-aminobutyric acid. The measurements of specific radio-activities and of the approaches to /sup 14/C saturation of some amino acids indicate the presence and relative sizes of metabolically active and passive pools of these amino acids. Added ammonia decreased carbon fixation into carbohydrates and increased fixation into carboxylic acids and amino acids. The results indicate that added ammonia stimulates the reactions mediated by pyruvate kinase and phosphenoenolpyruvate carboxylase, as seen with other plant systems. The data on the effects of added ammonia on total labeling, pool sizes, and specific radioactivities of several amino acids provides a number of indications about the intracellular sites of principal synthesis from carbon skeletons of these amino acids and the selective nature of effects of increased intracellular ammonia concentration on-such synthesis.

• Research Organization: Univ. of California, Berkeley
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6570455
• Journal Information: Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 68; ISSN PLPHA
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
AMMONIA
BIOLOGICAL EFFECTS
BIOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON DIOXIDE FIXATION
CARBON OXIDES
CARBOXYLASE
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
ENZYMES
FOOD
HYDRIDES
HYDROGEN COMPOUNDS
LABELLED COMPOUNDS
LIGASES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PLANT CELLS
SPINACH
STIMULATION
SYNTHESIS
TRANSFERASES
VEGETABLES