Heparin binding to cobra basic phospholipase A2 depends on heparin chain length and amino acid specificity.
Heparin is shown to bind specifically to the carboxy-terminal region of toxic type I phospholipase A2 from Naja nigricollis (N-PLA2) by competition assay using synthetic polypeptides and heparin affinity chromatography. The binding strength is seen to depend on heparin chain length and the presence of N-sulfate groups of heparin. It is observed that both electrostatic and non-electrostatic interactions are involved in the specific binding of heparin to the carboxy-terminus. When heparin's size is at least a decasaccharide, about two molecules of N-PLA2 bind to one molecule of heparin, as evidenced by the chemical estimate of protein to carbohydrate ratio in such N-PLA2/heparin complexes. Based on such a stoichiometric measurement and computer modeling of the N-PLA2/heparin complex, it is suggested that the binding sites of the two N-PLA2 molecules on one heparin molecule lie on the opposite sides of the heparin chain.
Department of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan.
Y H
YH
Lin
S C
SC
Lee
P Y
PY
Chang
P K
PK
Rajan
S C
SC
Sue
W G
WG
Wu
D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002846:Chromatography, Affinity; D003198:Computer Simulation; D004546:Elapid Venoms / Q000201:enzymology*; D006493:Heparin / Q000378:metabolism*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011485:Protein Binding; D055672:Static Electricity; D013329:Structure-Activity Relationship; D013463:Sulfuric Acid Esters
D004546:Elapid Venoms; D013463:Sulfuric Acid Esters; D006493:Heparin; D010741:Phospholipases A; D054467:Phospholipases A2