Transformation of PL to AA

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Within a cell, polyunsaturated fatty acids (PUFA) are stored at the sn-2 position on the glycerol backbone of membrane phospholipids. However, upon stimulation by an extracellular stimulus PUFAs are released from the cellular membrane via lipolysis \cite{Kramer1991}. This reaction is performed by the phospholipase A2 enzymes which are translocated to the membrane once activated \cite{Winstead2000, Six2001}. This results in the mobilisation of PUFAs into the cytosol, where they are consequently metabolised \cite{Lin1993, Pettus2004, Lambeau2008, Dennis2011, Norris2014, Leslie2015, Mouchlis2015}.

Reaction

Catalysed by cPLA2α (3.1.1.4).

Chemical equation

Phospholipid \rightleftharpoons Arachidonic Acid

Rate equation

R01.PNG

cPLA2a Parameters

Michaelis-Menten Constants
Value Units Species Notes Reference
0.05 mM Human Organism: Human

Expression vector:Insect cell pH: 9 Temperature: 37 C

Notes: Rheumatoid arthritic synovial fluid phospholipase A2

[1]
0.051 mM Human Organism: Human

Expression vector: Native Synovial Fluid pH: 9 Temperature: 37 C

Notes: Rheumatoid arthritic synovial fluid phospholipase A2

[1]
0.2 mM Human Organism: Human

Expression vector: Sus scrofa pH: 8 Temperature: 24 C

[2]
0.25 mM Snake Organism: ECHIS CARINATUS

Expression vector: ECHIS CARINATUS) Venom pH: 7.5 Temperature: Not stated

[3]
Michaelis-Menten Constants
Value Units Species Notes Reference
2.50E-03 mM Mouse Fibroblasts Cytosolic PLA2 [4]
5.00E-02 mM Human Recombinant PLA2 (Phosphatidylcholine as the substrate) [5]
2.00E-02 mM Human Recombinant PLA2 (Phosphatidylethanolamine as the substrate) [5]
4.13E-01 ± 2.80E-02 mM Rat PMN Neutrophils [6]


Enzyme Turnover Numbers
Value Units Species Notes Reference
2.6E+03± 0.1E+03 per minute Bos taurus Organism: Bovine

Expression Vector: Bovine pancreatic PLA2 pH: 7.5 Temperature:25'C


Substrate - 1,2-diheptanoyl-sn-glycero-3-phosphorylcholine. "From the molecular weight, 13,795, the catalytic center activity for the micellar substrate, Kcat{app}, was calculated."

[7]
3000 per minute Porcine Organism: Porcine

Expression Vector: Porcine Enzme: Pancreatic phospholipase A, Substrate: 1,2-dipalmitoyl-phosphatidylcholine, Enzyme concentration: 0.2 mg/ml, pH: 8.0. Temperature: 41 C

[8]
11220 per minute Stingray Expression Vector: Stingray

Enzyme: Secreted pH:8.5 Temperature: 40 °C

[9]
8400 per minute Camel Expression Vector: Camel

Enzyme: Pancreatic pH: 8.5 Temperature: 40 °C

[9]
cPLA2 Abundance
Value Units Species Notes Reference
8.26 ppm Human Expression Vector: Lung

Enzyme: cPLA2 pH: 7.5 Temperature: 37 °C

[10]
42.8 ppm Human Expression Vector: Uterine cervix

Enzyme: 5-LOX pH: 7.5 Temperature: 37 °C

[11]
111 ppm Human Expression Vector: Oral Cavity

Enzyme: cPLA2 pH: 7.5 Temperature: 37 °C

[11]
30.8 ppm Human Expression Vector: Liver

Enzyme: cPLA2 pH: 7.5 Temperature: 37 °C

[11]
Gibbs Free Energy Change
Value Units Species Notes Reference
(-13.03833) kcal/mol Not stated Estimated

Enzyme: cPLA2 Substrate: Phosphatidylcholine Product: 1-acyl-sn-glycero-3-phosphocholine and a long-chain fatty acid pH: 7.3 ionic strength: 0.25

[12]

References

  1. ↑ 1.0 1.1 Kawauchi Y “Preparation and characterization of human rheumatoid arthritic synovial fluid phospholipase A2 produced by recombinant baculovirus-infected insect cells.” J Biochem. 1994 Jul;116(1):81-7.
  2. ↑ Yu BZ “Kinetic and structural properties of disulfide engineered phospholipase A2: insight into the role of disulfide bonding patterns.” Biochemistry. 2005 Mar 8;44(9):3369-79.
  3. ↑ A.H. Mohamed “Purification of a basic phospholipase A2 from Indian Saw-Scawled Viper (Echis carinatus) venom: characterization of antigenic, catalytic and pharmacological properties” Toxicon 32, 1187-1196 (1994).
  4. ↑ Spaargaren M. “Characterization and identification of an epidermal-growth-factor-activated phospholipase A2.” Biochem J. 1992 Oct 1; 287(Pt 1): 37–43.
  5. ↑ 5.0 5.1 Kawauchi Y. “Preparation and characterization of human rheumatoid arthritic synovial fluid phospholipase A2 produced by recombinant baculovirus-infected insect cells.” J Biochem. 1994 Jul;116(1):81-7.
  6. ↑ Kawauchi Y. “Changes in kinetic properties of cytosolic phospholipase A2 in activated rat neutrophils.” Adv Exp Med Biol. 1997;433:439-42.
  7. ↑ [www.ncbi.nlm.nih.gov/pubmed/8454568 Hada S. “Hydrolysis of Micellar Diheptanoylphosphatidylcholine Catalyzed byBovine Pancreatic Phospholipase A2: Kinetic Characterization of Group I and II Enzymes1” J Biochem (1993) 113 (1): 13-17.]
  8. ↑ [http://www.jbc.org/content/261/12/5328.long Menashe M. “Hydrolysis of Dipalmitoylphosphatidylcholine Small Unilamellar Vesicles by Porcine Pancreatic Phospholipase A2” J Biochem (1986) 261, 5328-5333.]
  9. ↑ 9.0 9.1 Bacha B. “Purification and biochemical characterization of pancreatic phospholipase A2 from the common stingray Dasyatis pastinaca” Lipids Health Dis. 10, 32 (2011)
  10. ↑ M. Kim A draft map of the human proteome Nature, 2014 509, 575–581
  11. ↑ 11.0 11.1 11.2 M. Wilhelm Mass-spectrometry-based draft of the human proteome Nature, 2014 509, 582–587
  12. ↑ Caspi et al 2014, "The MetaCyc database of metabolic pathways and enzymes and the BioCyc collection of Pathway/Genome Databases," Nucleic Acids Research 42:D459-D471

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