ENZYMATIC-ACTIVITY OF CYTOCHROME-C-OXIDASE INSERTED INTO MAGNETOLIPOSOMES DIFFERING IN SURFACE-CHARGE DENSITY

The role played by the surface charge density of the phospholipid coat of nanometer-sized Fe3O4 colloids (so-called ''magnetoliposomes'') in the catalytic activity of beef heart cytochrome c oxidase was investi gated. Screening of various binary mixtures of the anionic dimyristoyl phosphatidylglycerol and the zwitterionic dimyristoylphosphatidylcholi ne demonstrated that the highest degree of reactivation was found in t he lower negative charge range. Pre-incubation of the charged colloida l biocatalytic particles with cytochrome c induced aggregation and red uced overall enzymatic activity. The results are interpreted in terms of a different affinity of the substrate for the various membrane type s and of a reorganisation of the enzyme within the membrane matrices.