Acetylhydrolase activity

H. J. Milionis, M. S. Elisaf, S. A. Karabina, E. Bairaktari, A. D. Tselepis and K. C. Siamopoulos, Plasma and Lp(a)-Associated PAF-Acetylhydrolase Activity in Uremic Patients Undergoing Different Dialysis Procedures, Kidney International 56(6) (1999) 2276-2285. 

Chapman, M.J., Elisaf, M., Tselepis, A.D. Atorvastatin preferentially reduces LDL-associated platelet-activating factor acetylhydrolase activity in dyslipidemias of type IIA and type IIB. ArterwsclerTTum 2002 22 306-11. 

At the end of our experiment (45 days), plasma PAF-acetylhydrolase activity was significantly elevated in group B (atherogenic diet supplemented with GSBPL) compared to group A (atherogenic diet), which may be attributed to the increased HDL-cholesterol levels, since this enzyme is partially located on the HDL particles. 

This result could be explained on the basis of the elevated PAF-acetylhydrolase activity in the plasma of rabbits of group B. This study shows that polar hpids of cultured gilthead sea bream (Sparns auratd) contain bioactive micro-constituents, PAF inhibitors, that inhibit PAF activity both in vitro and in vivo, consequently inhibiting early atherosclerosis development. The above data reinforce the beneficial effect of cultured gilthead sea bream polar lipids against atherosclerosis development (Nasopoulou et al., 2010). 

Adachi, T, Aoki, J, Manya, H, Asou, H, Aral, H and Inoue, K (1997) PAF analogues capable of inhibiting PAF acetylhydrolase activity suppress migration of isolated rat cerebellar granule cells. Neurosci Lett, 235, 133-136. 

FIGURE 25.24 Platelet activating factor, formed from Talkyl-2-lysophosphatidylcholine by acetylation at C-2, is degraded by the action of acetylhydrolase. 

Vadas P, Gold M, Perelman B, Liss GM, Lack G, Blyth T Simons FE, Simons JK, Cass D, Yeung J Platelet-activating factor, PAF acetylhydrolase, and severe anaphylaxis. N Engl J Med 2008 358 28-35. 

It is possible that nematode-secreted AChEs act on alternative substrates to ACh. We had previously suggested, on the basis of structural similarity, that platelet-activating factor (PAF), a potent phospholipid mediator of inflammation, might represent such an alternative substrate (Blackburn and Selkirk, 1992b) but subsequent studies demonstrated that purified AChEs did not cleave PAF, and the enzyme responsible for this activity in secreted products of N. brasiliensis, PAF acetylhydrolase, was purified and defined as a distinct heterodimeric protein (Grigg et al., 1996). Although an open mind on the subject sould be kept, the strict substrate specificity of the nematode-secreted AChEs suggests that they most likely act on ACh alone. 

Blackburn, C.C. and Selkirk, M.E. (1992b) Inactivation of platelet activating factor by a putative acetylhydrolase from the gastrointestinal nematode parasite Nippostrongylus brasiliensis. Immunology 75, 41 -A 6. 

Grigg, M.E., Gounaris, K. and Selkirk, M.E. (1996) Characterisation of a platelet-activating factor acetylhydrolase secreted by the nematode parasite Nippostrongylus brasiliensis. BiochemicalJournal 317, 541-547. 

Complement factor H and platelet-activating factor acetylhydrolase polymorphisms and hemolytic uremic syndrome due to E. coli 0157... 

Xu H, Iijima K, Shirakawa T et al. Platelet-activating factor acetylhydrolase gene mutation in Japanese children with Escherichia coli 0157-associated hemolytic uremic syndrome. Am J Kidney Dis 2000 36[1] 42—46. 

Hendrickson, H. S., Hendrickson, E. K., Johnson, I. D. and Farber, S. A. (1999). Intramolecularly quenched BODIPY-labeled phospholipid analogs in phospholipase A(2) and platelet-activating factor acetylhydrolase assays and in vivo fluorescence imaging. Anal. Biochem. 276, 27-35. 

Hattori,M.,Adachi, H.,Tsujimoto, M.,Arai,H. and Inoue, K. Miller-Diecker lissencephaly gene encodes a subunit of brain platelet-activating factor acetylhydrolase. Nature 370 216-218,1994. 

Miller-Dieker Syndrome De novo Platelet-activating factor acetylhydrolase... 

C-Esterases are found in the IUBMB classification under the entry acetyl-esterase (acetic ester acetylhydrolase, EC 3.1.1.6). Doubts have been expressed about the existence of C-esterases [56], Indeed, their activation by sodium 4-(hydroxymercurio)benzoate is not reproducible, and paraoxon has at least slight inhibitory effects on these esterases. 

Hakkinen, T, Luoma, JS, Hiltunen, MO, Maephee, CH, Milliner, KJ, Patel, L, Rice, SQ, Tew, DG, Karkola, K, and Yla-Herttuala, 1999, Lipoprotein-associated phosphohpase A(2), platelet-activating factor acetylhydrolase, is expressed by macrophages in human and rabbit atherosclerotic lesions, Arterioscler. Thromb. Vase. Biol. 19 2909-2917. 

Soluble TNF-ot receptors bind to TNF-a (a pro-inflammatory cytokine), limiting its activity (Buescher and Williams-Koeppen, 1998). Plateletactivating factor acetylhydrolase (PAF-AH) degrades PAP, thereby limiting the gastrointestinal mucosal injury caused by PAP (Furukawa et al, 1993). 

Sawaragi. Influence of a cigarette smoke extract on the hormonal regulation of platelet-activating factor acetylhydrolase in rats. Biol Reprod 1995 53(2) 244-252. 

Chi EY, Weickmann J, Carpenter JF, Manning MC, Randolph TW. Heterogeneous nucleation-controlled particulate formation of recombinant human platelet-activating factor acetylhydrolase in pharmaceutical formulation. J Pharm Sci 2005 94(2) 256-274. 

Stafforini DM, Sheller JR, Blackwell TS, Sapirstein A, Yuli FE, McIntyre TM, Bonventre JV, Prescott SM, Roberts LJ 2nd. Release of free F2-isoprostanes from esterified phospholipids is catalyzed by intracellular and plasma platelet-activating factor acetylhydrolases. J. Biol. Chem. 2006 281 4616. 

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