Electron spin resonance study of serum lipoproteins of salmon (Oncorhynchus kisutch): Structural alterations produced in high density lipoproteins by mercury and cadmium.

High denisty lipoproteins from the serum of salmon (Oncorhynchus kisutch), containing a maleimide spin label (4-male-imido-2,2,6,6-tetramethylpiperidinooxyl), were exposed to HgCl2, CdCl2, and CH3HgCl under physiological conditions. Electron spin resonance spectrometry revealed that HgCl2 and CdCl2 produce significant alterations at sites representing weakly and strongly immobilized label. The observed changes appear to be taking place primarily in the surface architecture. No alterations were found in the normal spectra of high density lipoproteins exposed to CH3HgCl under similar conditions. Each metal species binds strongly with the apo-high density lipoproteins; however, marked differences exist in the effects produced upon high density lipoprotein structure by the inorganic ions and CH3HgCl.