Gossypol binds to a high‐affinity binding site on human serum albumin

Abstract

The triterpene gossypol competes with bilirubin for a high‐affinity binding site on human serum albumin. Similar competition between bilirubin and gossypol occurs in the binding of these ligands to the glutathione S‐transferases from human liver and placenta. In each case, gossypol and bilirubin exhibit similar binding constants. The binding properties of gossypol may generally mimic those of bilirubin.

Effect of replacing soybean meal with cottonseed meal on growth, hematology, antioxidant enzymes activity and expression for juvenile grass carp, Ctenopharyngodon idellus

“…So the growth depression of fish fed diets containing 68 and 100% of CSM (containing 136.54 ± 8.14 and 205.83 ± 8.17 mg free gossypol/kg diet, respectively) may have been attributed to the toxicity of free gossypol and less available lysine. In addition, free gossypol is a major lipid-soluble substance that binds with blood proteins and cell membranes with high-affinity after ingestion (Royer and Vander Jagt 1983; Reyes and Benos 1988). …”

Albumin Thiolate Anion Is an Intermediate in the Formation of Albumin-S–S-Homocysteine

“…These ligands probably become disulfide bonded in the plasma, because the albumin that is formed and secreted from the liver is in the free thiol form (17). Certain drugs containing thiol groups also bind to Cys 34 of albumin (19,21,22 to be the most probable binding site for low molecular weight thiols including homocysteine. In an earlier study where plasma proteins were resolved by gel filtration chromatography, it appeared that homocysteine was associated with albumin; however, the mechanism of homocysteinylation was not addressed (23).…”

Inhibition of testicular LDH-X from laboratory animals and man by gossypol and its isomers

“…These observations would also indicate why apparent selectivity was seen in the present experiments. Human serum albumin binds with very high affinity :o gossypol, KD about 1 10~9mol/l (Royer & van der Jagt, 1983), which is several orders of magnitude higher than the affinity of gossypol for LDH-X that can be surmised from the EC-50 :oncentrations, 15-70 10~6 mol/1. Serum contains~34 mg albumin/ml (Diem & Lentner, 1970) and so is present in a large excess and would bind gossypol, possibly by the lysine residues, and so decrease the concentration to which enzymes were exposed.…”