Binding of radioiodinated human. beta. -endorphin to serum proteins from rats and humans, determined by several methods

Journal Article · Mon Oct 07 00:00:00 EDT 1985 · Life Sci.; (United States)

DOI:https://doi.org/10.1016/0024-3205(85)90246-2· OSTI ID:5254492

Sato, H; Sugiyama, Y; Sawada, Y; Iga, T; Hanano, M

Binding of immunoreactive radioiodinated human ..beta..-endorphin (/sup 125/I-..beta..-EP) to rat serum was demonstrated by gel filtration of /sup 125/I-..beta..-EP in pooled rat serum on Sephadex G-200. Two radioactive peaks associated with proteins eluted from the column. The first peak eluted at the void volume containing lipoproteins, ..cap alpha../sub 2/- and ..beta../sub 2/-macroglobulins, and the second peak at the fraction of albumin. Binding of /sup 125/I-..beta..-EP to albumin was directly proved by gel filtration of /sup 125/I-..beta..-EP in buffer containing 4% human serum albumin on Sephadex G-200. Equilibrium dialysis was not applicable to investigating the interaction of /sup 125/I-..beta..-EP with serum proteins, because of the intense nonspecific adsorption to the semi-permeable membrane and the degradation of the peptide during dialysis. Therefore, in order to quantitatively evaluate the binding of /sup 125/I-..beta..-EP in sera from rats and humans, the authors utilized four other methods (ultrafiltration, charcoal adsorption, polyethylene glycol precipitation and equilibrium gel filtration). These methods corresponded well with each other and indicated 35-44% binding of /sup 125/I-..beta..-EP in rat serum. Binding of /sup 125/I-..beta..-EP in normal human serum was 36%, determined by ultrafiltration. Serum protein binding of /sup 125/I-..beta..-EP was concentration independent over the concentration range studied (1-1000 nM). 23 references, 4 figures, 1 table.

• Research Organization: Univ. of Tokyo, Japan
• OSTI ID: 5254492
• Journal Information: Life Sci.; (United States), Vol. 37:14
• Country of Publication: United States
• Language: English

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550201* - Biochemistry- Tracer Techniques