The structural and functional essentiality of the N-terminal alpha-helix in the phospholipase A2 of the Taiwan banded krait.
In order to identify the structural and functional essentiality of the N-terminal alpha-helix of Bungarus multicinctus PLA2 for its enzymatic activity, comparative studies of the biochemical properties of native and recombinant PLA2 were made. It was found that the appearance of a Met residue preceding the N-terminus Asn-1 of the recombinant protein appreciably affected PLA2 activity and the hydrophobic character of the ANS-binding site. Additionally, the charged state and the hydrophobicity of the molecular surface changed as well. However, removal of the N-terminal Met-1 from the recombinant PLA2 resulted in the production of a fully active PLA2, whose biochemical properties were indistinguishable from those of the native enzyme. These observations, together with the findings that the helical wheel plot of the N-terminal alpha-helix showed distinct hydrophobic and hydrophilic faces and that the ANS-binding site was the active site of PLA2 enzymes, suggest that the hydrophobic face of the N-terminal alpha-helix in native PLA2 should be in the interior of the enzyme molecule for binding with ANS and the phospholipid/substrate.
Chang
L S
LS
Department of Biochemistry, Kaohsiung Medical College, Taiwan, ROC.
Chang
C C
CC
Wu
P F
PF
D000818:Animals; D001665:Binding Sites; D017838:Bungarus; D002384:Catalysis; D016297:Mutagenesis, Site-Directed; D010741:Phospholipases A / Q000737:chemistry* / Q000235:genetics; D054467:Phospholipases A2; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013329:Structure-Activity Relationship
D011994:Recombinant Proteins; D010741:Phospholipases A; D054467:Phospholipases A2