REGULATION OF CATALYTIC ACTIVITY AND SUPRAMOLECULAR STRUCTURE OF ANGIOTENSIN-CONVERTING ENZYME IN REVERSED MICELLES OF AEROSOL OT IN OCTANE

Regulation of the catalytic activity and supramolecular structure of a ngiotensin-converting enzyme from bovine lungs was studied in reversed micelles of aerosol OT (AOT) in octane. The curve for the dependence of enzymatic activity on the degree of surfactant hydration (micelle s ize) has two maxima, at hydration degrees ([H2O]/[AOT]) 27 and 31. Vel ocity sedimentation data suggest that depending on the hydration degre e, the angiotensin-converting enzyme is present in the reversed micell es either as monomers or as dimers, the latter being catalytically act ive. In contrast to aqueous media, in the reversed micelles angiotensi n-converting enzyme does not require chloride for catalytic activity. In the reversed micelles of AOT in octane, the holoenzyme is stable, w hile the apoenzyme is rapidly and irreversibly inactivated. Incorporat ion of Zn2+ into the active site of the apoenzyme was observed only in the presence of substrate or an inhibitor.