Specific gonadotropin binding to Pseudomonas maltophilia.

Abstract

Binding of 125I-labeled human chorionic gonadotropin to P. maltophilia is dependent on time, temperature and pH, and the binding to this procaryotic species is hormone-specific and saturable. The equilibrium Kd is 2.3 .times. 10-9 M. There are no cooperative interactions between binding sites (Hill coefficient, 1.05). The number of sites is estimated as 240 fmol/100 .mu.g of protein. NaCl and KCl, at concentrations from 1-10 mM, have no effect on binding. Divalent cations (Mg2+ and Ca2+ and 1 mM EDTA inhibit hormone binding. Binding is destroyed by heat or by treatment with Pronase or .alpha.-chymotrypsin and is increased by phospholipase C. Binding of the labeled gonadotropin is not observed with other gram-negative organisms, e.g., Escherichia coli, P. testosteroni, P. aeruginosa, Enterobacter aerogenes or E. cloacae. [Steroid hormones may influence the infectivity of certain bacteria.].