title: Roles of lysine residues and N-terminal alpha-amino group in membrane-damaging activity of Taiwan cobra cardiotoxin 3 toward anionic and zwitterionic phospholipid vesicles.
abstract: In contrast to a slight increase in activity toward phosphatidylcholine (EYPC)/dimyristoyl phosphatidic acid (DMPA) vesicles, guanidination of Naja naja atra cardiotoxin 3 (CTX3) and selective trinitrophenylation of N-terminal alpha-amino group enhanced notably membrane-damaging activity on EYPC/egg yolk sphingomyelin (EYSM) vesicles. Chemically modified CTX3 showed a reduction in its hemolytic activity and cytotoxicity. These reflected that membrane-damaging activity of CTX3 was affected by phospholipid compositions. Phospholipid-binding capability and oligomeric assembly upon binding with lipid vesicles did not closely correlate with membrane-damaging potency of native and modified CTX3. Moreover, different topographical contacts and distinctive modes for the binding of CTX3 and its modified derivatives with anionic phospholipid vesicles (EYPC/DMPA) and zwitterionic phospholipid vesicles (EYPC/EYSM) were observed. Compared with in the case of EYPC/DMPA, the interaction between CTX molecules and EYPC/EYSM was drastically reduced by increasing salt concentration and heparin. Taken together, our data indicate that guanidination of Lys residues and trinitrophenylation of alpha-amino group alter differently the interacted modes upon absorption on anionic phospholipid vesicles and zwitterionic phospholipid vesicles. The findings also suggest that positively charged residues of CTX3 play a distinctive role in damaging anionic and zwitterionic phospholipid vesicles.
authors: Institute of Biomedical Sciences, National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
authors: Yi-Ling
authors: YL
authors: Chiou
authors: Pei-Hsiu
authors: PH
authors: Kao
authors: Wen-Hsin
authors: WH
authors: Liu
authors: Shinne-Ren
authors: SR
authors: Lin
authors: Long-Sen
authors: LS
authors: Chang
mesh_terms: D002942:Circular Dichroism; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry* / Q000633:toxicity*; D003124:Colorimetry; D004354:Drug Screening Assays, Antitumor; D004546:Elapid Venoms / Q000737:chemistry / Q000633:toxicity; D004912:Erythrocytes / Q000187:drug effects; D005456:Fluorescent Dyes; D006146:Guanidines / Q000737:chemistry; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D008239:Lysine / Q000737:chemistry*; D008566:Membranes / Q000737:chemistry / Q000187:drug effects; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D012235:Rhodamines; D013109:Sphingomyelins / Q000737:chemistry; D013329:Structure-Activity Relationship; D020298:U937 Cells
chemical_list: D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D005456:Fluorescent Dyes; D006146:Guanidines; D008055:Lipids; D008081:Liposomes; D010713:Phosphatidylcholines; D010743:Phospholipids; D012235:Rhodamines; D013109:Sphingomyelins; C082202:cardiotoxin III, Naja naja atra; D008239:Lysine