title: Functional characteristics of a phospholipase A(2) inhibitor from Notechis ater serum.
abstract: A phospholipase A(2) inhibitor has been purified p6om the serum of Notechis ater using DEAE-Sephacel chromatography. The inhibitor was found to be composed of two protein subunits (alpha and beta) that form the intact complex of approximately 110 kDa. The alpha-chain is a 30-kDa glycoprotein and the beta-chain a nonglycosylated, 25-kDa protein. N-terminal sequence analysis reveals a high level of homology to other snake phospholipase A(2) inhibitors. The inhibitor was shown to be extremely pH and temperature stable. The inhibitor was tested against a wide variety of phospholipase A(2) enzymes and inhibited the enzymatic activity of all phospholipase A(2) enzymes tested, binding with micromole to nanomole affinity. Furthermore, the inhibitor was compared with the Eli-Lilly compound LY311727 and found to have a higher affinity for human secretory nonpancreatic phospholipase A(2) than this chemical inhibitor. The role of the carbohydrate moiety was investigated and found not to affect the in vitro function of the inhibitor.
authors.affiliation: Toxin Research Group, Department of Cell and Molecular Biology, University of Technology, Westbourne St., Gore Hill, Sydney 2065, Australia.
authors.forename: P G
authors.initials: PG
authors.lastname: Hains
authors.forename: K L
authors.initials: KL
authors.lastname: Sung
authors.forename: A
authors.initials: A
authors.lastname: Tseng
authors.forename: K W
authors.initials: KW
authors.lastname: Broady
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D017815:Elapidae / Q000097:blood*; D004791:Enzyme Inhibitors / Q000097:blood* / Q000737:chemistry / Q000494:pharmacology; D006023:Glycoproteins / Q000097:blood* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010741:Phospholipases A / Q000037:antagonists & inhibitors*; D017386:Sequence Homology, Amino Acid; D012910:Snake Venoms; D013816:Thermodynamics
chemical_list: D004791:Enzyme Inhibitors; D006023:Glycoproteins; D007211:Indoles; C095553:LY 311727; C403969:NaI protein, Notechis ater; D012910:Snake Venoms; D010741:Phospholipases A