Covalent binding of an intermediate(s) in prostaglandin biosynthesis to tissue protein: T.E. Eling, A.G.E. Wilson, A. Chaudhari, A. Kung, D.J. Crutchley, H. Hawkins, M. Anderson. National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709

Abstract

This chapter describes the chemical instability of 15-keto- 13,14-dihydro-PGE2 under various conditions, the development of a radioimmunoassay (RIA)for the stable bicyclic degradation product, and conditions for the induced quantitative conversion of 15-ketodihydro-PGE2 in biological samples into this product prior to measurements. 15-ketodihydro-PGA2 undergo a different fate cyclization into a bicyclic product, l l-deoxy-15-keto-13,14-dihydro- 1 lβ,16ξ-cyclo-PGE2. This cyclization product contains at least two epimeric sites, at C-8 and C-16; furthermore, the cyclization of the PGA2 derivative might also involve a transient formation of the corresponding PGC2 compound, resulting in additional epimeric sites at C-11 and C-12. The radioimmunoassay described in this chapter is developed using a racemic mixture of these epimers for the preparation of the immunogen. The crucial point RIA is the prior quantitative conversion of all 15-ketodihydro-PGE2 present in the sample into the bicyclic derivative before analysis.