Biology:Phospholipase A1

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Phospholipase A1.jpg
Crystallographic structure of Phospholipase A1. Red region denotes alpha helices, Green region denotes loops, and yellow region denotes beta sheets.
EC number3.1.1.32
CAS number9043-29-2
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
phospholipase A1 member A
NCBI gene51365
Other data
EC number3.1.1.32
LocusChr. 3 q13.13-13.2

Phospholipase A1 encoded by the PLA1A gene is a phospholipase enzyme which removes the 1-acyl.[1] Phospholipase A1 is an enzyme that resides in a class of enzymes called phospholipase that hydrolyze phospholipids into fatty acids.[2] There are 4 classes, which are separated by the type of reaction they catalyze. In particular, phospholipase A1 (PLA1) specifically catalyzes the cleavage at the SN-1 position of phospholipids, forming a fatty acid and a lysophospholipid.[3][4]

Phospholipase A1 cleaves phospholipid at the SN1 position forming a lysophospholipid and a fatty acid.


PLA1's are present in numerous species including humans, and have a variety of cellular functions that include regulation and facilitation of the production of lysophospholipid mediators, and acting as digestive enzymes. These enzymes are responsible for fast turnover rates of cellular phospholipids.[5] In addition to this, the products of the reaction catalyzed by PLA1 which are a fatty acid and a lysophospholipid are important in various biological functions such as platelet aggregation and smooth muscle contraction.[6] In addition, lysophospholipids can be found as surfactants in food techniques and cosmetics, and can be used in drug delivery.[7] Since PLA1 is found in many species, it has been found that there are different classes of this one specific enzyme based on the organism being studied.[8][9]

Species and tissue distribution

There are many variations of PLA1, differing slightly between each organism it is present in. Most notably, it can be found in mammalian cells such as plasma of rat livers and bovine brains, and can also be found in metazoan parasites, protozoan parasites, and snake venom.

Substrate specificity

PLA1 hydrolyzes nonionic substrates preferentially over ionic substrates. Optimum pH conditions for PLA1 activity on neutral phospholipids is around 7.5, whereas the optimal conditions for PLA1 activity on acidic phospholipids is around 4.[10][11]


The structure of a PLA1 is a monomer that contains the following sequence: Gly-X-Ser-X-Gly, where X represents any other amino acid. The serine is considered the active site in the enzyme.[12] PLA1's also contain a catalytic triad of Ser-Asp-His, with a variety of cysteine residues needed for disulfide bond formation. The cysteine residues are responsible for key structural motifs such as the lid domain and the B9 domain, both of which are lipid binding surface loops. These two loops can vary between each PLA1. For example, a PLA1 enzyme with a long lid domain (22-23 amino acids) and a long B9 domain (18-19 amino acids) constitute an extracellular PLA1 exhibiting triacylglycerol hydrolase activity.[13] In contrast, a PLA1 enzyme that is considered more selective will have a short lid and B9 domain that span 7-12 and 12-13 amino acids, respectively.

Industrial use

Unlike other phospholipases such as PLA2, there is much that is unknown about PLA1 due to the lack of any efficient way to purify, clone, express, and characterize this enzyme.[13] PLA1 is currently commercially unavailable because of this. Lysophospholipids can be found as surfactants in food techniques and cosmetics, and can be used in drug delivery. Current research is being applied to determine suitable growth environments for PLA1 production. In one particular study, it was found that PLA1 can be produced by S. cerevisiae and A. oryzae. In these PLA1 producing cultures, increasing the nitrogen and carbon sources can lead to increase in PLA1 yields.[8]


In the early 1900s, an observation was made, showing an accumulation of free fatty acids after incubation of pancreatic juice with phosphatidylcholine. One of the first cases of observed PLA1 activity was on 1903 when snake venom was found to alter phosphatidylcholine into lysophosphatidylcholine, which is defined as a phosphatidylcholine without one of its fatty acids. In the 1960s, it was discovered to be that enzymes catalyze this fatty acid cleavage in multiple ways, one of which is the sn-1 position. This particular reaction is catalyzed by PLA1, while the reaction at the sn-2 position is catalyzed by phospholipase A2.

See also


  1. Phospholipase+A1 at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. "Characterization of phospholipase A1, A2, C activity in Ureaplasma urealyticum membranes". Mol. Cell. Biochem. 201 (1–2): 159–67. 1999. doi:10.1023/A:1007082507407. PMID 10630635. 
  3. "Phospholipases A1". International Journal of Molecular Sciences 12 (1): 588–612. 2011. doi:10.3390/ijms12010588. PMID 21340002. 
  4. "A membrane-bound phospholipase A1 purified from Escherichia coli". Biochemistry 10 (24): 4447–56. November 1971. doi:10.1021/bi00800a015. PMID 4946924. 
  5. "Identification of phospholipase A 1 and A 2 in the soluble fraction of rat liver lysosomes". Biochemistry 10 (10): 1942–6. May 1971. doi:10.1021/bi00786a031. PMID 4397924. 
  6. "Phospholipase A1 Structures, Physiological and Patho-physiological Roles in Mammals". Lipases and phospholipases in drug development : from biochemistry to molecular pharmacology. Weinheim: Wiley-VCH. 2004. p. 23. doi:10.1002/3527601910.ch2. ISBN 9783527306770. 
  7. Pichon R (Jun 1975). "[Recent acquisitions on the treatment of perinatal infections].". Maroc Med 55 (591): 280–5. PMID 1177510. 
  8. 8.0 8.1 "High-level secretory production of phospholipase A1 by Saccharomyces cerevisiae and Aspergillus oryzae.". Biosci Biotechnol Biochem 65 (1): 94–101. Jan 2001. doi:10.1271/bbb.65.94. PMID 11272851. 
  9. "Intracellular phospholipase A1 and acyltransferase, which are involved in Caenorhabditis elegans stem cell divisions, determine the sn-1 fatty acyl chain of phosphatidylinositol.". Mol Biol Cell 21 (18): 3114–24. Sep 2010. doi:10.1091/mbc.E10-03-0195. PMID 20668164. 
  10. "Phospholipases of Mineralization Competent Cells and Matrix Vesicles: Roles in Physiological and Pathological Mineralizations". International Journal of Molecular Sciences 14 (3): 5036–129. 2013. doi:10.3390/ijms14035036. PMID 23455471. 
  11. "Purification and properties of a membrane-bound phospholipase A1 from Mycobacterium phlei.". J Biol Chem 249 (17): 5658–67. Sep 1974. PMID 4415399. 
  12. "Structure and function of extracellular phospholipase A1 belonging to the pancreatic lipase gene family". Biochimie 89 (2): 197–204. 2007. doi:10.1016/j.biochi.2006.09.021. PMID 17101204. 
  13. 13.0 13.1 "Structure and function of phosphatidylserine-specific phospholipase A1". Biochim Biophys Acta 1582 (1–3): 26–32. May 2002. doi:10.1016/s1388-1981(02)00134-8. PMID 12069807.