title: Kinetics and mechanism of the interaction between human serum albumin and monomeric haemin.
abstract: The interaction of human serum albumin with monomeric haemin has been investigated by detailed kinetic analysis in dimethyl sulphoxide/water (3:5, v/v). The results obtained under conditions of albumin saturation of haemin and under pseudo-single turnover conditions indicate that methaemalbumin is formed in a two-stage, single-intermediate process. The initial association between the haemin and human serum albumin is a chemically controlled process (k1 = 1.7 X 10(5) mol-1 . s-1 . dm3 at 24 degrees C); the variation of K1 with pH exhibited a well defined pK of 5.9. The overall equilibrium constant, calculated by using microscopic rate constants, is 1.1 (+/- 0.5) X 10(8) mol-1 at 24 degrees C. The data and conclusions are consistent with a general binding mechanism for albumin in which intermediate formation is followed by an entropy-controlled internalization of the ligand.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D004121:Dimethyl Sulfoxide; D006418:Heme / Q000031:analogs & derivatives; D006427:Hemin; D006801:Humans; D007700:Kinetics; D008956:Models, Chemical; D011485:Protein Binding; D012709:Serum Albumin; D013053:Spectrophotometry; D014867:Water
chemical_list: D012709:Serum Albumin; D014867:Water; D006418:Heme; D006427:Hemin; D004121:Dimethyl Sulfoxide