[Enzyme immunoassay of (24R)-brassinosteroids].

Brassinosteroids are a new group of phytohormones that are widely distributed in plants and play an important role in the processes of plant growth and development. Physiological concentrations of brassinosteroids in plants are extremely low, and their analysis in organs and tissues is very difficult. This study is devoted to the chemical aspects of elaboration and to bioanalytical parameters of an immunoenzymatic system for quantitative determination of the phytohormones 24-epicastasterone and 24-epibrassinolide.

[Catalytic activity of steroid conjugates of various types of peroxidases in aqueous and micellar media].

The horseradish peroxidase (HRP) conjugates with the sheep antirabbit antibodies and cortisol (COR) or progesterone (PROG) containing 9 to 40 steroid molecules per HRP molecule were synthesized. In aqueous media all the conjugates have lower catalytic activity in the o-phenylenediamine oxidation than the native enzyme. In reversed Aerosol OT micelles in heptane the HRP-COR and HRP-PROG conjugates containing 12 and 9 steroid molecules, respectively, have catalytic constants 2.

[Peroxidase activity of catalase modified by progesterone].

Catalase conjugates with 3, 7, 9 and 42 progesterone molecules were obtained by the reaction between the enzyme and N-oxy-succinimide ether of 3-0-carboxymethyloxime of progesterone. The enzyme modified by 42 progesterone molecules is effective in o-dianisidine oxidation by hydrogen peroxide and has a kcat/KM value of 512 M-1 s-1. The catalase conjugates with 3, 7 and 9 progesterone molecules exhibit a high activity during o-dianisidine oxidation by cumene hydroperoxide.