Synonyms: 3-PGKc, cytosolic 3-phosphoglycerate kinase
Species: Spinacia oleracea
A protein with 3-phoshoglycerate kinase activity was purified from a crude extract of spinach (Spinacia oleracea L.). In fact two isoforms of the protein were identified through this procedure: one is cytosolic (this protein), the other chloroplastic (see plastidic 3-phosphoglycerate kinase). The chloroplastic protein was also purified from isolated chloroplasts, allowing the exact determination of the identity of each crude extract-purified isoform [KopkeSecundo90]. The cytosolic protein has a molecular weight of 39 kDa by size exclusion chromatography (40.7 kDa on SDS-PAGE). The protein is monomeric. Its pH optimum is at 7.5 with a strong drop of activity at higher and lower pH values [KopkeSecundo90].
Molecular Weight of Polypeptide: 39 kD (experimental) [KopkeSecundo90 ]
|Cellular Component:||GO:0005829 - cytosol [KopkeSecundo90]|
Enzymatic reaction of: 3-phosphoglycerate kinase
EC Number: 18.104.22.168
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.
This reaction is reversible.
In Pathways: superpathway of cytosolic glycolysis (plants), pyruvate dehydrogenase and TCA cycle , superpathway of anaerobic sucrose degradation , glycolysis IV (plant cytosol) , sucrose biosynthesis I (from photosynthesis)
The protein does not follow Michaelis-Menten kinetics for this reaction. The kinetics are biphasic and the enzyme exhibits 4-6 times higher affinity for the substrate in the lower concentration range than in the higher range [KopkeSecundo90].
Low concentration range: Km (MgATP) 240 μM, Km (3-PGA) 280 μM.
High concentration range: Km (MgATP) 1460 μM, Km (3-PGA) 1220 μM.
Primary Physiological Regulators of Enzyme Activity: ATP
pH(opt): 7.5 [KopkeSecundo90]
KopkeSecundo90: Kopke-Secundo E., Molnar I., Schnarrenberger C. (1990). "Isolation and characterization of the cytosolic and chloroplastic 3-phosphoglycerate kinase from spinach leaves." Plant Physiol. 93:40-47.
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