A chromatographic method was employed to study the kinetics of human serum albumin (HSA) adsorbed on immobilized monoclonal antibodies. The antibodies of various specificities were covalently bound to a high-performance liquid chromatography (HPLC) silica support. For very low desorption rates, successive amounts of the reacting protein were injected until column saturation. The analysis of the increase of the non-retained fraction calculated from peak area measurements gives the capacity of the support and the rate of the biospecific adsorption process. The model is based on a second-order Langmuir kinetic law and assumes a global mass transfer for the adsorption process. The use of a silica support of small pore size permits the reduction of the contribution for mass transfer in the stagnant fluid and the decrease in the column capacity: due to its large size, the reacting molecule is adsorbed on the external surface of the particle. The adsorption rate constants of HSA on five monoclonal anti-HSA antibodies of different specificities were determined. For all the immuno-adsorbents studied, the adsorption rate constant is significantly lower than that found on immobilized polyclonal antibodies. Measurements at different flow rates reveal that the mass transfer due to the transport to the adsorbent surface is small and can be estimated.

Adsorption↗

PubMedDate not supplied

[Antigenic structure of a fragment of human serum albumin].

The antigenic structure of a fragment (F1) of human serum albumin (HSA), carrying one of the antigenic sites of the whole molecule, has been studied. Previous studies have shown that this fragment is made of two peptide chains linked by a disulfide bond. One of these chains named alpha has 28 residues and one intrachain disulfide bond giving rise to a loop of 9 or 10 residues. The chain occurs under two forms: the beta chain made of 25 residues and the gamma chain which differs from the beta chain by the absence of the two last C-terminal residues (F. Bellon and C. Lapresle, Biochem. J., 1975, 147, 585-592). The alpha and beta chains both inhibit independantly at 100% the agglutination by an anti-albumin serum of red cells sensitized with F1. Chains alpha, beta and gamma displace anti-HSA antibodies fixed upon an immunoadsorbent prepared with F1. Chain alpha is more active than chain beta which in turn is more active than chain gamma. Reduction and alkylation of alpha and beta chains abolish almost completely their immunological activity. Immunoadsorbents prepared with alpha or beta chains adsorb all of the anti-F1 antibodies from an anti-HSA serum. Antibodies isolated from each chain are inhibited by both chains. Chains alpha and beta induce in rabbits the formation of antibodies reacting with F1 and HSA, alpha chain being a better immunogen than beta chain.

Aminobenzoates↗