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]
Enzymatic reaction of: 3-phosphoglycerate kinase
EC Number: 22.214.171.124-phospho-D-glycerate + ATP ⇄ 1,3-bisphospho-D-glycerate + ADP
The direction shown, i.e. which substrates are on the left and right sides, 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.Inhibitors (Other): ATP [KopkeSecundo90]
Primary Physiological Regulators of Enzyme Activity: ATPKinetic Parameters:
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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