Cytosolic ATP-dependent phosphofructokinase from spinach

• Published in: Plant physiology (Bethesda) Vol. 84; no. 2; pp. 205 - 207
• Main Authors: Hausler, R.E, Holtum, J.A.M, Latzko, E
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.06.1987
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ADENOSINE TRIPHOSPHATE; ADENOSINTRIFOSFATO; Agronomy. Soil science and plant productions; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Chloroplasts; Communications; Economic plant physiology; Enzymes; Enzymes and enzyme inhibitors; ENZYMIC ACTIVITY; FOSFATOS; Fractionation; Fundamental and applied biological sciences. Psychology; Leaves; Metabolism and Enzymology; Nutrition. Photosynthesis. Respiration. Metabolism; Oxidases; PHOSPHATE; PHOSPHATES; Plants; PLASTE; PLASTIDIOS; PLASTIDS; PROTOPLASTE; PROTOPLASTO; PROTOPLASTS; Quaternary ammonium compounds; Spinach; SPINACIA OLERACEA; Sulfates; TRANSFERASAS; TRANSFERASE; TRANSFERASES; Vegetals; Enzyme; Dicotyledones; Angiospermae; Spermatophyta; Spinacia oleracea; Chenopodiaceae; 6-Phosphofructokinase
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.84.2.205

ATP-dependent 6-phosphofructokinase (PFK) activity is present in both chloroplastic and in nonchloroplastic fractions isolated from spinach protoplasts. The activity in the extra-chloroplastic fraction was stimulated 2- to 3.5-fold by 25 mM inorganic phosphate (Pi), the chloroplast-associated activity was inhibited 2- to 5-fold. The Pi stimulated activity was ATP-dependent and was not an artifact due to the presence of fructose 6-P, Pi, pyrophosphatase, and pyrophosphate fructose 6-P 1-phosphotransferase (PFP). PFK activities, which expressed characteristics similar to those separated from protoplasts, could be separated following ammonium sulfate fractionation of crude extracts; the ammonium sulfate treatment also separated both PFK activities from PFP. It is concluded that spinach leaves contain a cytosolic PFK. This activity is relatively stable, is stimulated by Pi over a wide pH range, is not a result of the transformation of another enzyme activity, and has an activity that is similar to, or slightly less than, that of the cytosolic PFP.