Phospholipase A2 inhibition and modification by manoalogue

Reynolds, Laure J.; Morgan, Bradley; Hite, G. A.; Mihelich, Edward D.; Dennis, Edward A.

doi:10.1021/ja00223a044

Cited by 69 publications

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“…Amino acid analysis of the manoalide-modified cobra venom PLA2 (Lombardo & Dennis, 1985) and protection from enzyme inactivation by exogenous lysine (Bennett et al, 1987) suggested that lysine residues were being modified, probably by nucleophilic addition of an amino group to one or more of the carbonyl groups present in the inactivator. Synthetic analogues of manoalide were prepared in order to define the pharmacophore for the inhibition of PLA2 (Reynolds et al, 1988;Glaser et al, 1989). Inhibition studies indicated that hydrocarbons containing only the 4-hydroxy-Zbutenolide ring were inhibitory but the loss of activity was reversible (Deems et al, 1987).…”

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“…Inhibition studies indicated that hydrocarbons containing only the 4-hydroxy-Zbutenolide ring were inhibitory but the loss of activity was reversible (Deems et al, 1987). A compound termed "manoalogue" was prepared that contained the cu,&unsaturated aldehyde functional group of manoalide's hemiacetal ring in addition to a butenolidecontaining hydrocarbon (Reynolds et al, 1988) (Scheme I). This compound was found to produce a time-dependent irreversible loss of PLA2 activity similar to that of manoalide.…”

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“…These results suggested that both aldehydes present in manoalide (open form) are required for irreversible addition; however, the exact structure of the adduct remains to be elucidated. Reynolds et al (1988) have shown that manoalogue modified 3-4 lysine residues in the cobra venom (Naja naja naja) enzyme and one of these is probably lysine 6. It is not yet known whether the active site or the interfacial binding site is being modified.…”

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Kinetic characterization of phospholipase A2 modified by manoalogue

et al. 1991

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Manoalogue, a synthetic analogue of the sea sponge-derived manoalide, has been previously shown to partially inactivate the phospholipase A2 from cobra venom (Reynolds, L. J., Morgan, B. P., Hite, E. D., Mihelich, E. D., & Dennis, E. A. (1988) J. Am. Chem. Soc. 110, 5172) by reacting with enzyme lysine residues. In the present study, the inactivation of the phospholipases A2 from pig pancreas, bee venom, and cobra (Naja naja naja) venom by manoalogue was studied in detail. Manoalogue-treated enzymes were examined in the scooting mode on vesicles of 1,2-dimyristoyl-sn-glycero-3-phosphomethanol. Here the native enzymes bound irreversibly to the vesicles and hydrolyzed all of the phospholipids in the outer monolayer without leaving the surface of the interface. All three manoalogue-treated enzymes showed reduced catalytic turnover for substrate hydrolysis in the scooting mode, and the modified enzymes did not hop from one vesicle to another. Thus, inactivation by manoalogue is not due to the decrease in the fraction of enzyme bound to the substrate interface. This result was also confirmed by fluorescence studies that directly monitored the binding of phospholipase A2 to vesicles. A chemically modified form of the pig pancreatic phospholipase A2 in which all of the lysine epsilon-amino groups have been amidinated was not inactivated by manoalogue, indicating that the modification of lysine residues and not the amino-terminus is required for the inactivation. Several studies indicated that the manoalogue-modified enzymes contain a functional active site. For example, studies that monitored the protection by ligands of the active site from attack by a alkylating agent showed that manoalogue-modified pig phospholipase A2 was capable of binding calcium, a substrate analogue, lipolysis products, and a competitive inhibitor. Furthermore, relative to native enzymes, manoalogue-modified enzymes retained significantly higher catalytic activities when acting on water-soluble substrates than when acting on vesicles in the scooting mode. Intact manoalogue had no affinity for the catalytic site on the enzyme as it did not inhibit the enzyme in the scooting mode and it did not protect the active site from alkylation. Pig pancreatic phospholipase A2 bound to micelles of 2-hexadecyl-sn-glycero-3-phosphocholine was resistant to inactivation by manoalogue, suggesting that the modification of lysine residues on the interfacial recognition surface of the enzyme was required for inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

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Kinetic characterization of phospholipase A2 modified by manoalogue

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“…An example is manoalide (MLD), a natural marine product, and its synthetic analogue manoalogue (MLG), both able to cause an irreversible inhibition of snake venom PLA 2 s [14,118]. Comparative studies on the action of both agents on snake and bee venom PLA 2 s have been reported [15], showing similar kinetic effects in all cases.…”

Section: Artificial Inhibitors Of Svpla 2 Smentioning

confidence: 99%

Snake Venom Phospholipase A2 Inhibitors: Medicinal Chemistry and Therapeutic Potential

Marcussi¹,

Sant’Ana²,

Oliveira³

et al. 2007

CTMC

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Phospholipases A2 (PLA2s) are commonly found in snake venoms from Viperidae, Hydrophidae and Elaphidae families and have been extensively studied due to their pharmacological and physiopathological effects in living organisms. This article reports a review on natural and artificial inhibitors of enzymatic, toxic and pharmacological effects induced by snake venom PLA2s. These inhibitors act on PLA2s through different mechanisms, most of them still not completely understood, including binding to specific domains, denaturation, modification of specific amino acid residues and others. Several substances have been evaluated regarding their effects against snake venoms and isolated toxins, including plant extracts and compounds from marine animals, mammals and snakes serum plasma, in addition to poly or monoclonal antibodies and several synthetic molecules. Research involving these inhibitors may be useful to understand the mechanism of action of PLA2s and their role in envenomations caused by snake bite. Furthermore, the biotechnological potential of PLA2 inhibitors may provide therapeutic molecular models with antiophidian activity to supplement the conventional serum therapy against these multifunctional enzymes.

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“…Inhibitors of phospholipase A # (PLA # ) enzymes have been identified in fungi [1], bacteria [2,3] and plants [4][5][6][7][8][9][10] and in human [11,12], bovine [13,14] and pig serum [15]. Additionally, heparin and heparan sulphate [16,17], lipocortin [18][19][20], lung surfactant protein A [21] and, uniquely, peptides of PLA # enzymes themselves [22] have been shown to inhibit PLA # enzymic activity.…”

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confidence: 99%

Purification and inhibitory profile of phospholipase A2 inhibitors from Australian elapid sera

Hains

Broady

2000

Biochemical Journal

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Although the resistance of snakes to their own venom is well known, until now no investigators have examined the serum of Australian snakes. Here we describe the identification and purification of a range of phospholipase A2 (PLA2) inhibitors from the serum of Australian elapids. All PLA2 inhibitors were composed of two protein chains, an α-chain and a β-chain. The α-chains were approx. 22.5 kDa in size and variably glycosylated, whereas the β-chains were approx. 19.8 kDa in size and not glycosylated. Identification of isoforms of the two subunit chains was significant because three of the six sera examined were from single snake specimens. In addition, the glycosylation patterns of the α-chains were thoroughly investigated in these unpooled sera. The functional and structural properties of the purified inhibitors were studied. Uniquely, a snake PLA2 inhibitor was found to inhibit human type II PLA2 enzyme, which has implications for the treatment of the many diseases in which PLA2 enzymes have been implicated. Further, we demonstrate that the inhibitor forms a non-covalent association with a purified PLA2 enzyme. Finally, the purified PLA2 inhibitor was shown to protect in vivo against the lethal affects of a homologous PLA2 enzyme, suggesting a role for PLA2 inhibitors in the treatment of snake bite victims.

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Phospholipase A2 inhibition and modification by manoalogue

Cited by 69 publications

References 1 publication

Kinetic characterization of phospholipase A2 modified by manoalogue

Kinetic characterization of phospholipase A2 modified by manoalogue

Snake Venom Phospholipase A2 Inhibitors: Medicinal Chemistry and Therapeutic Potential

Purification and inhibitory profile of phospholipase A2 inhibitors from Australian elapid sera

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