INTERFACIAL CATALYSIS BY PHOSPHOLIPASES AT CONJUGATED LIPID VESICLES - COLORIMETRIC DETECTION AND NMR-SPECTROSCOPY

Background: Self-assembled conjugated polymers are rapidly finding bio logical and biotechnological applications. This work describes a synth etic membrane system based on self-assembled polydiacetylenes, which a re responsive to the enzymatic activity of phospholipases - a ubiquito us class of enzymes that catalyze the hydrolysis of phospholipid molec ules embedded in cell membranes. Results: We show that phospholipases are active at bilayer vesicles composed of the natural enzyme substrat e, dimyristoylphosphatidylcholine (DMPC), and a synthetic pi-conjugate d polymerized lipid based on polydiacetylene (PDA). In addition, the e nzymatic reaction induces an optical transition in the surrounding PDA matrix, visible to the naked eye. Nuclear magnetic resonance spectros copy confirms the occurrence of enzymatic catalysis and reveals the fa te of the cleavage products. Conclusions: The results indicate that th e structural and color changes of the PDA matrix are directly related to interfacial catalysis by phospholipase. This novel biocatalytic met hod of inducing optical transitions in conjugated polymers might lead to new approaches towards rapidly screening new enzyme inhibitor compo unds.