title: Dual role of interfacial phospholipid in phospholipase A2 catalysis.
abstract: The results of crosslinking experiments with dimethyl suberimidate and gel filtration binding studies are used to delineate a detailed model for phospholipase A2(phosphatide 2-acyl-hydrolase, EC 3.1.1.4) action in the presence of Ca2+ on mixed micelles of Triton X-100 and phospholipid. Important features of the "dual-phospholipid" model are: (i) the use of the nonionic surfactant as an inert matrix that may influence lipid conformation but does not interact with the enzyme; (ii) the involvement of two lipid molecules in a single cycle of catalysis as an explanation for the "surface dilution" phenomenon; (iii) the requirement of an ordered reaction whereby divalent metal ion binds prior to phospholipid binding; and (iv) the induction by lipid substrate of an asymmetric dimer structure for the enzyme.
mesh_terms: D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002384:Catalysis; D002850:Chromatography, Gel; D007093:Imidazoles; D008823:Micelles / Q000378:metabolism; D008954:Models, Biological; D010740:Phospholipases / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D011092:Polyethylene Glycols; D012910:Snake Venoms / Q000378:metabolism; D013329:Structure-Activity Relationship; D013997:Time Factors; D015032:Zinc / Q000378:metabolism
chemical_list: D007093:Imidazoles; D008823:Micelles; D010743:Phospholipids; D012910:Snake Venoms; D011092:Polyethylene Glycols; D010740:Phospholipases; D015032:Zinc; D002118:Calcium
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