Luber-Narod J, Boyd N D, Leeman S E
Department of Physiology, University of Massachusetts Medical School, Worcester 01655.
Eur J Pharmacol. 1990 Apr 25;188(4-5):185-91. doi: 10.1016/0922-4106(90)90001-e.
The inhibitory effect of guanine nucleotides on the binding of 125I-Bolton-Hunter conjugated substance P (125I-BHSP) to rat submaxillary gland membranes has been confirmed and further explored. The evidence presented here indicates that this is due to a marked loss of binding affinity. In the presence of 5'-guanylyl imidodiphosphate (GppNHp) there is (1) a greater than or equal to 20-fold increase in the Kd as determined by Scatchard analysis and (2) the concentration of SP required to inhibit half of the 125I-BHSP binding (IC50) increased approximately 30-fold. Consistent with a marked decrease in affinity is an approximately 100-fold increase in the rate of dissociation of 125I-BHSP following addition of GppNHp. Complete restoration of high-affinity binding was achieved by removal of the guanine nucleotide.
鸟嘌呤核苷酸对125I-博尔顿-亨特偶联P物质（125I-BHSP）与大鼠颌下腺膜结合的抑制作用已得到证实并作了进一步研究。此处提供的证据表明，这是由于结合亲和力显著丧失所致。在5'-鸟苷酰亚胺二磷酸（GppNHp）存在的情况下，（1）通过Scatchard分析测定，解离常数（Kd）增加了20倍或更多，（2）抑制125I-BHSP结合一半所需的P物质（SP）浓度（IC50）增加了约30倍。与亲和力显著降低相一致的是，加入GppNHp后，125I-BHSP的解离速率增加了约100倍。通过去除鸟嘌呤核苷酸，可完全恢复高亲和力结合。
