Biochemical and molecular characterization of purified chicken pancreatic phospholipase A2

Abstract

Chicken pancreatic phospholipase A(2) (ChPLA(2)) was purified from delipidated pancreases using ammonium sulfate and ethanol precipitation, followed by sequential column chromatography steps on MonoQ Sepharose and size exclusion HPLC columns. ChPLA(2) was found to be a nonglycosylated monomeric protein with a molecular mass of 14 kDa and a specific activity of 400 U x mg(-1) in the presence of 1 mM sodium taurodeoxycholate and 4 mM CaCl(2) with phosphatidylcholine as substrate. The N-terminal sequence of the first 15 amino acids of ChPLA(2) was determined, and showed a high degree of homology with known mammal pancreatic phospholipases A(2). The gene encoding the mature ChPLA(2) was cloned and sequenced. The deduced amino acid sequence of the mature ChPLA(2) confirmed the high level of identity with mammal pancreatic PLA(2). To investigate the structure-activity relationships, a 3D model of group IB ChPLA(2) was built using the porcine pancreatic phospholipase A(2) structure as template.