The structural and functional contribution of N-terminal region and His-47 on Taiwan cobra phospholipase A2.
Modification of His-47 and removal of the N-terminal octapeptide caused a different effect on the structure of Naja naja atra (Taiwan cobra) phospholipase A2 (PLA2). Unlike native enzyme, Ca2+ induced an alteration in the structural flexibility of His-modified PLA2. Moreover, the spatial positions of Trp residues in His-modified PLA2 were not properly rearranged toward lipid-water interface in the presence of Ca2+. CD spectra and fluorescence measurement showed that the dynamic properties of Trp residues and the gross conformation of N-terminally truncated PLA2 were totally different from native enzyme. Although a precipitous drop in the enzymatic activity was observed with modified PLA2, His-modified PLA2 and N-terminally truncated PLA2 retained cytotoxicity on inducing necrotic death of human neuroblastoma SK-N-SH cells. Our data suggest that structural perturbations elicited by the chemical modification cause a dissociation of enzymatic activity and cytotoxicity of PLA2.
Kao
Pei-Hsiu
PH
Institute of Biomedical Sciences, National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
Chen
Ku-Chung
KC
Lin
Shinne-Ren
SR
Chang
Long-Sen
LS
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002942:Circular Dichroism; D004546:Elapid Venoms / Q000737:chemistry* / Q000633:toxicity; D017815:Elapidae; D006639:Histidine / Q000737:chemistry*; D006801:Humans; D006868:Hydrolysis; D054510:Phospholipases A2, Cytosolic / Q000737:chemistry* / Q000502:physiology; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology*; D013329:Structure-Activity Relationship
D004546:Elapid Venoms; D006639:Histidine; D054510:Phospholipases A2, Cytosolic; D002118:Calcium