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Phospholipase A 2 from Trypanosoma congolense : Characterization and haematological properties
Author(s) -
Nok Andrew J.,
Esievo King A. N.,
Ibrahim Sani,
Ukoha Agwu I.,
Ikediobi Christopher O.
Publication year - 1993
Publication title -
cell biochemistry and function
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 61
eISSN - 1099-0844
pISSN - 0263-6484
DOI - 10.1002/cbf.290110208
Subject(s) - enzyme , arrhenius plot , phosphatidylcholine , chemistry , biochemistry , phospholipase , phospholipid , activation energy , membrane , organic chemistry
Abstract Phospholipase A 2 was isolated from Trypanosoma congolense and purified to electrophoretic homogeneity. The enzyme appeared to exist in a dimeric form with subunit molecular weights of 16 500 and 18 000. It had a pH optimum of 6·8. Kinetic analysis with different substrates, showed that the enzyme had exceptional specificity for 1,2,dimyristoyl‐ sn ‐phosphatidylcholine and 1,2,dioleoyl‐ sn ‐phosphatidylcholine with K m values of 1·85 × 10 −3 M and 2·12 × 10 −3 M respectively. The Arrhenius plot was linear with an activation energy of 5·8 kcal mol −1 . Inhibition studies with parahydroxymercuribenzoate and tri‐butyltinoxide were positive thus implicating a thiol group at the catalytic site of the enzyme. The enzyme was stable to heat treatment and possessed haemolytic and anticoagulating properties.