A membrane enzyme is an enzyme whose functional organization includes association with a biological lipid membrane. Membrane-associated phospholipases bind lipid interfaces and position their catalytic sites to act on phospholipid substrates [1]. Membrane adenylyl cyclases connect signals received at the cell surface with conversion of intracellular ATP to cyclic AMP [2]. The membrane environment also places lipid substrates beside catalytic regions that receive soluble reactants from an adjacent aqueous compartment [3]. In ATP synthase, a membrane-associated ion-translocation system is mechanically coupled to catalytic subunits that form ATP [4]. These arrangements connect enzyme chemistry to membrane topology. Substrate access, orientation of domains, and interactions with surrounding lipids establish how the enzyme operates at or across the bilayer [5].
Lipid Membrane Structure and Behavior·Molecular Biology·Biochemistry, Genetics and Molecular Biology·Life Sciences