Soluble and insoluble ternary complexes of serum proteins with polyanions in the presence of Cu2+ in water

✍ Scribed by M. Mustafaev; B. Cìrakoğlu; S. Sarac; S. Öztürk; F. Yücel; E. Bermek

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 872 KB
• Volume: 62
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19961003)62:1<99::aid-app13>3.0.co;2-3

✦ Synopsis

Complex formation between polyacrylic acid (PAA) and bovine serum albumin (BSA), human serum albumin (HSA), hemoglobin (Hb), globin (GI), and, respectively, transferrin (Tr), were studied in neutral water. Water-soluble and insoluble complexes are formed upon addition of divalent copper ions to the solution. T h e contacts between proteins and PAA are achieved via chelate unit formation in which the copper ions are located a t the center. T h e solubility o f t h e polycomplexes depends on the nature of proteins and correlates with their isoelectric points (PI). In the mixtures of Hb-Cu2+-PAA and G1-Cu2+-PAA, insoluble complexes are formed a t p H = PI starting with very low concentrations of Cu2+ (nCu/nAA I 0.01). On the other hand, these polycomplexes remain soluble a t p H > PI. BSA, HSA, and T r form soluble ternary polycomplexes at neutral water (pH 7). T h e formation of the polycomplexes in the mixture BSA-Cu2+-PAA was intensively studied by titration, HPLC, electrophoretic, and spectrophotometric methods. T h e solubility, composition, and stability of these polycomplexes depend on metal/polymer and protein/polymer ratio. Insoluble polycomplexes are formed when concentration of Cu2+ reaches a critical value (ncu/ nAA 2 0.25). At this concentration ofCu*+, phase separation takes place, starting with very low concentration of protein in the system. Over the critical ratio of the protein/polymer, the mixture again exhibits water-soluble character. T h e pattern of distribution of Cu2+ between PAA coils and of protein globules between polymer-metal complex particules appeared t o follow the self-assembly principle. A hypothetical structural scheme for the formation of soluble and insoluble ternary polycomplexes is proposed. 0