Identification and properties of very high affinity brain membrane-binding sites for a neurotoxic phospholipase from the taipan venom

Journal Article · Wed Jul 05 04:00:00 EDT 1989 · Journal of Biological Chemistry; (USA)

OSTI ID:5564636

Lambeau, G; Barhanin, J; Schweitz, H; Qar, J; Lazdunski, M ^[1]

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1. Centre de Biochimie, Nice (France)

Four new monochain phospholipases were purified from the Oxyuranus scutellatus (taipan) venom. Three of them were highly toxic when injected into mice brain. One of these neurotoxic phospholipases, OS2, was iodinated and used in binding experiments to demonstrate the presence of two families of specific binding sites in rat brain synaptic membranes. The affinities were exceptionally high, Kd1 = 1.5 +/- 0.5 pM and Kd2 = 45 +/- 10 pM, and the maximal binding capacities were Bmax 1 = 1 +/- 0.4 and Bmax 2 = 3 +/- 0.5 pmol/mg of protein. Both binding sites were sensitive to proteolysis and demonstrated to be located on proteins of Mr 85,000-88,000 and 36,000-51,000 by cross-linking and photoaffinity labeling techniques. The binding of {sup 125}I-OS2 to synaptic membranes was dependent on Ca2+ ions and enhanced by Zn2+ ions which inhibit phospholipase activity. Competition experiments have shown that, except for beta-bungarotoxin, a number of known toxic snake or bee phospholipases have very high affinities for the newly identified binding sites. A good correlation (r = 0.80) was observed between toxicity and affinity but not between phospholipase activity and affinity.

• OSTI ID: 5564636
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 264:19; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
AMINO ACID SEQUENCE
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BODY
BRAIN
CALCIUM COMPOUNDS
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CENTRAL NERVOUS SYSTEM
CHARGED PARTICLES
CHEMICAL PROPERTIES
CHEMICAL REACTIONS
CHROMATOGRAPHY
CROSS-LINKING
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
ELECTROPHORESIS
ELEMENTS
ENZYME ACTIVITY
ENZYMES
FRACTIONATION
HYDROLASES
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIPASE
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
METALS
MICE
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
NERVE CELLS
NERVOUS SYSTEM
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PEPTIDE HYDROLASES
POLYMERIZATION
POTASSIUM
PROTEINS
RADIOISOTOPES
REACTION KINETICS
REAGENTS
RECEPTORS
RODENTS
SEPARATION PROCESSES
SERINE PROTEINASES
SODIUM
SOMATIC CELLS
TRACER TECHNIQUES
TRYPSIN
VENOMS
VERTEBRATES
ZINC COMPOUNDS