Article,
Enzymatic probes of lipoprotein structure. Hydrolysis of human serum low density lipoprotein-2 by phospholipase A2.
J Biol Chem, 251 (12): 3823--3830 (June 1976)
Abstract
Pure phospholipase A, from Crotalus atroz is able to hydrolyze all the phosphatidylcholine,
phosphatidylserine, and phosphatidylethanolamine of human serum low density lipoprotein (LDL,). In
accord with the substrate specificity of the enzyme, sphingomyelin, other minor lipids and proteins are
not hydrolyzed. The enzyme-modified particles remain water-soluble and, upon reisolation, contain all of
the lysophospholipids and free fatty acids produced during the reaction. By electron microscopic, circular
dichroic, analytical ultracentrifugal, immunologic, and small angle x-ray scattering techniques, the
enzyme-modified particles exhibit only modest changes when compared with native LDL,. Accumulation
of negative charges on the lipoprotein during hydrolysis results in the repression of ionization of the free
fatty acid products. This electrostatic effect can be analyzed in terms of the Linderstrpm-Lang model
which yields an equivalent spherical radius of - 100 A for the particles.
