Richert N D, Ryan R J
Proc Natl Acad Sci U S A. 1977 Mar;74(3):878-82. doi: 10.1073/pnas.74.3.878.
Binding of 125I-labeled human chorionic gonadotropin to Pseudomonas maltophilia is dependent on time, temperature, and pH and the binding to this procaryotic species is hormone-specific and saturable. The equilibrium dissociation constant is 2.3 X 10(-9) M. There are no cooperative interactions between binding sites (Hill coefficient, 1.05). The number of sites is estimaated as 240 fmol/100 mug of protein. NaCl and KCl, at concentrations from 1 to 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 of 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, Pseudomonas testosteroni, Pseudomonas aeruginosa, Enterobacter aerogenes, or Enterobacter cloacae.
125I标记的人绒毛膜促性腺激素与嗜麦芽窄食单胞菌的结合取决于时间、温度和pH值，并且与这种原核生物的结合具有激素特异性和饱和性。平衡解离常数为2.3×10⁻⁹M。结合位点之间不存在协同相互作用（希尔系数为1.05）。结合位点的数量估计为240 fmol/100μg蛋白质。浓度为1至10 mM的NaCl和KCl对结合没有影响。二价阳离子（Mg²⁺和Ca²⁺）以及1 mM EDTA会抑制激素结合。加热或用链霉蛋白酶或α-胰凝乳蛋白酶处理会破坏结合，而磷脂酶C会增强结合。在其他革兰氏阴性菌中未观察到标记促性腺激素的结合，例如大肠杆菌、睾酮假单胞菌、铜绿假单胞菌、产气肠杆菌或阴沟肠杆菌。
