2-acyl-sn-glycero-3-phosphoethanolamine Lysophospholipase A2 Activity in Guinea-pig Heart Microsomes
Overview
Affiliations
We have recently described a lysophospholipase A2 activity in guinea-pig heart microsomes that hydrolyses 2-acyl-sn-glycero-3-phosphocholine (2-acyl-GPC). The presence of a similar activity that hydrolyses 2-acyl-sn-glycero-3-phosphoethanolamine (2-acyl-GPE) was not known. In this study, a lysophospholipase A2 activity in guinea-pig heart microsomes that hydrolyses 2-acyl-GPE has been characterized. The enzyme did not require Ca2+ for activity and exhibited a high specificity for 2-arachidonoyl-GPE and 2-linoleoyl-GPE over 2-oleoyl-GPE and 2-palmitoyl-GPE. The specificity for these unsaturated substrates was observed in the presence and absence of detergents. Selective hydrolysis of 2-arachidonoyl-GPE over 2-palmitoyl-GPE was observed when equimolar quantities of the two substrates were incubated with the enzyme. There was no preferential hydrolysis of either 2-linoleoyl- or 2-arachidonoyl-GPE when presented individually or as a mixture. Significant differences in the characteristics of 2-acyl-GPE-hydrolysing and 2-acyl-GPC-hydrolysing activities included differences in their optimum pH, the effect of Ca2+ and their acyl specificities. Taken together, these results suggest that the two activities are catalysed by different enzymes. 2-Acyl-GPE lysophospholipase activity with a preference for 2-arachidonoyl-GPE over 2-oleoyl-GPE was observed in guinea-pig brain, liver, kidney and lung microsomes. Lysophospholipase A1 activity that catalyses the hydrolysis of 1-acyl-GPE was also present in guinea-pig heart microsomes and had different characteristics from the 2-acyl-GPE-hydrolysing activity, including a preference for saturated over unsaturated substrates. The 2-acyl-GPE lysophospholipase A2 activity appeared to be distinct from Ca(2+)-independent phospholipase A2. The characteristics of the 2-acyl-GPE lysophospholipase A2 suggest it could play a role in the selective release of arachidonic and linoleic acids for further metabolism in cells.
Richmond G, Smith T Int J Mol Sci. 2011; 12(1):588-612.
PMID: 21340002 PMC: 3039968. DOI: 10.3390/ijms12010588.
A novel phospholipase from Trypanosoma brucei.
Richmond G, Smith T Mol Microbiol. 2007; 63(4):1078-95.
PMID: 17238918 PMC: 3744940. DOI: 10.1111/j.1365-2958.2006.05582.x.
Badiani K, Arthur G Biochem J. 1995; 312 ( Pt 3):805-9.
PMID: 8554524 PMC: 1136186. DOI: 10.1042/bj3120805.
Sellner P, Phillips A Mol Cell Biochem. 1992; 117(2):119-25.
PMID: 1488044 DOI: 10.1007/BF00230750.
Badiani K, Lu X, Arthur G Biochem J. 1992; 288 ( Pt 3):965-8.
PMID: 1472009 PMC: 1131981. DOI: 10.1042/bj2880965.