Influence of chemistry in immobilization of cobra venom phospholipase A2: Implications as to mechanism

Phospholipase A2 from Naja naja kaouthia venom was covalently coupled onto agarose beads using two different chemistries. The effect of micellar competitive inhibitors in the coupling media was evaluated. Enzyme bound to N-hydroxysuccinimide-activated agarose, which is reactive primarily toward epsi...

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Bibliographic Details
Published in:Biochemistry (Easton) 1993-08, Vol.32 (32), p.8098-8102
Main Authors: Ferreira, Joao Paulo M, Sasisekharan, Ram, Louie, Otway, Langer, Robert
Format: Article
Language:English
Subjects:
Binding, Competitive
Biological and medical sciences
Biotechnology
Elapid Venoms - chemistry
Enzyme Activation
Enzymes, Immobilized
Fundamental and applied biological sciences. Psychology
Immobilization of enzymes and other molecules
Immobilization techniques
Methods. Procedures. Technologies
Micelles
Octoxynol
Phosphatidylcholines - metabolism
Phospholipases A - antagonists & inhibitors
Phospholipases A - chemistry
Phospholipases A - metabolism
Phospholipases A2
Phospholipids - metabolism
Polyethylene Glycols
Protein Binding
Sepharose
Succinimides
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Summary:Phospholipase A2 from Naja naja kaouthia venom was covalently coupled onto agarose beads using two different chemistries. The effect of micellar competitive inhibitors in the coupling media was evaluated. Enzyme bound to N-hydroxysuccinimide-activated agarose, which is reactive primarily toward epsilon-amino groups, had 20% activity retention against micellar diheptanoylphosphatidylcholine (DiC7-PC). Enzyme bound through carboxylic groups, using a modification of the carbodiimide method, had 50% retention. Similar relative activities were observed, for both conjugates, in monomeric dihexanoyl-PC and in mixed micelles of Triton X-100 with dipalmitoyl-PC or dioleoylphosphatidylethanolamine. The soluble form of the enzyme showed premicellar activation against monomeric DiC7-PC, while the immobilized form showed interfacial recognition at concentrations around the critical micellar concentration. These results suggest that the enzyme activity lost upon immobilization is a result of the inherent chemical modification of the enzyme and that enzyme oligomerization and interfacial recognition are not cause-effect phenomena.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00083a007