1,721,047 research outputs found
Attività ossidasiche in frumento duro e ricerca di inibitori dell'ossidazione dei pigmenti
No full textAn Improved Spectrophotometric Phospholipase A2 Assay Using 1-Palmitoyl-2-Linoleoyl-sn-Glycero-3- Phosphatidylcholine as Substrate and Lipoxygenase as Coupled Enzyme
No full textAn improved spectrophotometric assay of phospholipase A2 (PLA2) activity based on the coupled PLA2/lipoxygenase (LOX) reactions using 1-palmitoyl-2-linoleoyl-sn-glycero-3- phosphatidylcholine (PCLIN) as substrate is reported. The PLA2- mediated release of free linoleate is continuously monitored by following the absorbance increase at 234 nm caused by its conversion into the conjugated diene hydroperoxide catalyzed by the coupled soybean LOX-1 reaction. The new protocol includes the use of Tween 20 (3 μL/mmol phospholipid) as surfactant and of ethanol (15 μL/mL reaction mixture), that ensure clearness of reaction mixture and linear increase of absorbance in the course of reaction. This method was tested on a purified secretory PLA2 from honey bee venom (HBV-PLA2). The enzyme did not discriminate among PCLIN, phosphatidylcholine, and phosphatidylethanolamine, but showed the highest rate using 1,2- dilinoleoyl-sn-glycero-3-phosphatidylcholine (PCDILIN). Nevertheless, the use of PCDILIN is not recommended, as it may induce an overestimation of enzyme activity, because not only the free linoleate, but also the reaction product 1-linoleoyl-lysophosphatidylcholine, are known to be oxidized by LOX. HBV-PLA2 showed maximal activity at pH 9.0, hyperbolic kinetics (Km, 74.22.9 μM; Vmax, 8277 μmol/min/mg protein) and competitive inhibition (Ki about 5 μM) by palmityl trifluoromethyl ketone, a classical PLA2 inhibitor. Interestingly, the HBV-PLA2/soybean LOX-1 coupled reactions also allow an accurate assay of PCLIN concentration. In the whole, these results demonstrate that this improved PLA2/LOX assay allows a very accurate, simple, and rapid measurement of enzyme activity and substrate concentration
The presence of Phospholipase A2 activity in plant mitochondria as demonstrated by a new spectrophotometric assay
No full textRespirazione cianuro-insensibile e permeabilità al KCl in mitocondri di grano duro (Triticum durum Desf.)
No full textThe occurrence of a Phospholipase A2 activity in durum wheat (Triticum durum Desf.) mitochondria and its possible involvement in the response to hyperosmotic stress
No full textInibizione delle attività di lipossigenasi e di "bleaching" del beta-carotene in semola di grano duro
No full textEffect of K+ channel activity on the oxidative phosphorylation in durum wheat mitochondria from control and hyperosmotic stressed seedlings
No full textIs the uncoupling mitochondrial protein involved in durum wheat response to abiotic stress?
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