Determination of the binding of 2,4,5,2’,4’,5'‐hexachlorobiphenyl by low density lipoprotein and bovine serum albumin

Abstract

The mechanism of transport of polychlorinated biphenyls (PCB) to and from peripheral cells is not known. Plasma proteins, which bind a variety of compounds including hydrophobic molecules, are most likely to be involved in PCB transport. To study the role of lipoproteins in the transport and distribution of PCB to cells, an assessment of the nature and extent of the interaction and binding of PCB to plasma proteins was necessary. A simple filter assay procedure for the analysis of binding of 2,4,5,2'',4'',5''-hexachlorobiphenyl (HCB) by low density lipoproteins and serum albumin was described. The method allowed complete recovery of the PCB and reduced errors due to nonspecific binding to the apparatus to insignificant values. Low density lipoprotein bound HCB at several noninteractive sites (number of binding sites n = 30, binding constant K = 2.7 .times. 105, Kd = 7.2 .times. 10-6 M). Bovine serum albumin bound HCB at 1 noninteractive site (n = 0.53, K = 5.1 .times. 105, Kd = 1.9 .times. 10-6 M). Albumin and low density lipoprotein bound HCB effectively, and plasma proteins may play a role in its distribution to peripheral cells.