Interaction of Steroid--Peroxidase Conjugates with Cellulose Immunosorbents in Aqueous and Micellar Media

A. N. Eryomin and D. I. Metelitza^*

Institute of Bioorganic Chemistry, National Academy of Sciences of Belarus, Zhodinskaya ul. 5/2, Minsk, 220141 Belarus; fax: (0172) 63-7274; E-mail: ibochbel@ns.igs.ac.by

^* To whom correspondence should be addressed.

Received September 22, 1997; Revision received February 6, 1998

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In 0.1 M bicarbonate buffer (pH 9.0) and in microemulsions of aerosol OT (AOT) and its mixture with Triton X-45 in heptane, antibodies against cortisol (anti-COR) and progesterone (anti-PROG) were covalently immobilized on fine-porous cellulose filters (0.6 cm diameter) after sodium periodate oxidation. Immunosorbents obtained in different media were characterized in terms of antibody-bound density and antigen-binding capacity with respect to peroxidase--steroid conjugates HP--COR-11 and HP--PROG-4 containing 11 molecules of cortisol and four progesterone molecules, respectively. For all immunosorbents antigen-binding capacity expressed as peroxidase activity of immune complexes formed on the solid cellulose phase in aqueous and micellar media was determined. Dissociation constants of immunocomplexes on the cellulose formed in aqueous and micellar media were determined using ELISA. In all cases K_d values in aqueous media were ~10^-8 M and were significantly lower than corresponding values of dissociation constants of immune complexes in mixed microemulsions of AOT and Triton X-45.

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KEY WORDS: steroid--peroxidase conjugates, cortisol, progesterone, anti-steroid antibodies, immobilized antibodies, immunosorbents, immune complexes, dissociation constants of immune complexes, reversed micelles, microemulsions, antigen--antibody interaction, enzymes in nontraditional medium

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