Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.5 (neuropathy target esterase)
 1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mouse plasma platelet-activating factor acetylhydrolase (PAF-AH) has an apparent Km of 7.4 microM and a Vmax of 21.6 nmol/min per mg protein. Comparison with values reported for the human and the rat enzymes shows at least a 5-fold higher Vmax and similar enzyme-substrate affinity. Although lecithin:cholesterol acyltransferase (LCAT) and one component of the PAF-AH share similar masses and lipoprotein association, they are distinct enzymes. Similarly, PAF-AH is distinct from the phospholipase A2 (PLA2) and the lysophospholipase of mouse plasma. A series of PAF structural analogs showed either competitive inhibition or a mixed type of inhibition of PAF-AH. Mouse plasma PAF-AH is highly sensitive to 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) and is activated by deoxycholate. SDS-PAGE showed that two distinct proteins with molecular masses of 46 and 63 kDa contribute to the PAF-AH activity. The HDL-VHDL lipoprotein associated PAF-AH is precipitated to an extent of about 60% by phosphotungstate-MgCl2 and Tween 20 only partially solubilises the precipitated enzyme under conditions which can precipitate and solubilise the human enzyme.
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PMID:The mouse plasma PAF acetylhydrolase: I. Characterization and properties. 792 89

The occurrence of a 14-kDa secretory phospholipase A2 (PLA2) in guinea pig alveolar macrophages (AM) and its relationship with the release of arachidonic acid (AA) were investigated. Freshly collected AM showed no detectable PLA2 activity as measured by the in vitro hydrolysis of phosphatidic acid. However, the PLA2 activity increased progressively when AM were maintained in culture to reach a level 60- to 100-fold greater than basal values within 20 h, with a parallel secretion into the incubation medium. By contrast, the activities of other phospholipid-hydrolyzing enzymes (platelet-activating factor acetylhydrolase and lysophospholipase) were modified only marginally. Both intra- and extracellular increases of PLA2 activity were abrogated with actinomycin D or cycloheximide. The enhanced PLA2 activity preferentially hydrolyzed negatively charged phospholipids in the order phosphatidic acid > phosphatidylglycerol > phosphatidylethanolamine > phosphatidylcholine, had an optimum pH of 7.5, and required a millimolar Ca2+ concentration for optimal activity and an apparent molecular mass of 14 kDa. Taken together, these results suggest that cultured AM elaborate an enzyme similar to the group II PLA2. On the other hand, our results show that AM hydrolyzed exogenous 2-arachidonoyl phosphatidylcholine and released AA and metabolites on FMLP stimulation. However, in contrast to the increase observed in the activity of the 14-kDa PLA2, the enzymatic activity involved in the hydrolysis of 2-arachidonoyl phosphatidylcholine and AA release remained constant with the culture duration of AM. Finally, dexamethasone markedly inhibited the increase of PLA2 activity, but only marginally inhibited the release of AA and metabolites from FMLP-stimulated AM. We conclude that guinea pig AM elaborate a 14-kDa PLA2 similar to the group II PLA2 through RNA- and protein synthesis-dependent processes. This elaboration appears to be induced by the adhesion of AM and is clearly dissociated from the liberation of AA.
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PMID:Increased synthesis and secretion of a 14-kDa phospholipase A2 by guinea pig alveolar macrophages. Dissociation from arachidonic acid liberation and modulation by dexamethasone. 822 50

Mammalian tissues contain small form and large form lysophospholipases. Here we report the cloning, sequence, and expression of cDNA encoding the latter form of lysophospholipase using antibody raised against the enzyme purified from rat liver supernatant (Sugimoto, H., and Yamashita, S. (1994) J. Biol. Chem. 269, 6252-6258). The 2,539-base pair cDNA encoded 564 amino acid residues with a calculated Mr of 60,794. The amino-terminal two-thirds of the deduced amino acid sequence significantly resembled Escherichia coli asparaginase I with the putative asparaginase catalytic triad Thr-Asp-Lys and was followed by leucine zipper motif. The carboxyl-terminal region carried ankyrin repeat. When the cDNA was transfected into HEK293 cells, not only lysophospholipase activity but also asparaginase and platelet-activating factor acetylhydrolase activities were expressed. Reverse transcription-polymerase chain reaction revealed that the transcript occurred at high levels in liver and kidney but was hardly detectable in lung and heart from which large form lysophospholipases had been purified, suggesting the presence of multiple forms of large form lysophospholipase in mammalian tissues.
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PMID:Cloning and expression of cDNA encoding rat liver 60-kDa lysophospholipase containing an asparaginase-like region and ankyrin repeat. 957 12