TY - JOUR
T1 - Reversible, positive cooperative interaction of 11β-chloromethyl-[3H]estradiol-17β with the calf uterine estrogen receptor
AU - Sasson, Shlomo
AU - Katzenellenbooen, John A.
PY - 1989/11
Y1 - 1989/11
N2 - The binding of 11β-chloromethyl-[3H]estradiol-17β [3H]CME2) with the calf uterine estrogen receptor was investigated. The equilibrium binding analysis indicated a positive cooperative interaction yielding curvilinear Scatchard plots and Hill coefficients of 1.4-1.5. This positive cooperative interaction of [3H]CME2 was indistinguishable from the typical cooperative interaction of [3H]estradiol with the receptor. The apparent relative association constant and the relative binding affinity of CME2 for the estrogen receptor measured by competitive binding assay were 146 and 184%, respectively. The dissociation kinetics [3H]CME2 from the receptor was biphasic, composed of a fast dissociating component (15%, t 1 2 = 4 min at 0°C; 9%, t 1 2 = 4 at 28°C) and a slow dissociating component (85%,t 1 2 > 50 h at 0°C; 91 %, t 1 2 > 50 h at 28°C). The dissociation kinetics of [3H]estradiol was also biphasic: the t 1 2 of the fast dissociating component was 4 min at 0 and 28°C and ∼ 200 min for the slow dissociating component at both temperatures. The fraction of the slow [3H]estradiol dissociating component increased from 56 to 92% upon warming. Ethanol extraction and trichloroacetic acid treatment proved that the binding of [3H]CME2 is fully reversible. The unusual dissociation kinetics and the binding mechanism of CME; are discussed.
AB - The binding of 11β-chloromethyl-[3H]estradiol-17β [3H]CME2) with the calf uterine estrogen receptor was investigated. The equilibrium binding analysis indicated a positive cooperative interaction yielding curvilinear Scatchard plots and Hill coefficients of 1.4-1.5. This positive cooperative interaction of [3H]CME2 was indistinguishable from the typical cooperative interaction of [3H]estradiol with the receptor. The apparent relative association constant and the relative binding affinity of CME2 for the estrogen receptor measured by competitive binding assay were 146 and 184%, respectively. The dissociation kinetics [3H]CME2 from the receptor was biphasic, composed of a fast dissociating component (15%, t 1 2 = 4 min at 0°C; 9%, t 1 2 = 4 at 28°C) and a slow dissociating component (85%,t 1 2 > 50 h at 0°C; 91 %, t 1 2 > 50 h at 28°C). The dissociation kinetics of [3H]estradiol was also biphasic: the t 1 2 of the fast dissociating component was 4 min at 0 and 28°C and ∼ 200 min for the slow dissociating component at both temperatures. The fraction of the slow [3H]estradiol dissociating component increased from 56 to 92% upon warming. Ethanol extraction and trichloroacetic acid treatment proved that the binding of [3H]CME2 is fully reversible. The unusual dissociation kinetics and the binding mechanism of CME; are discussed.
UR - http://www.scopus.com/inward/record.url?scp=0024792392&partnerID=8YFLogxK
U2 - 10.1016/0022-4731(89)90233-1
DO - 10.1016/0022-4731(89)90233-1
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C2 - 2601330
AN - SCOPUS:0024792392
SN - 0022-4731
VL - 33
SP - 859
EP - 865
JO - Journal of Steroid Biochemistry
JF - Journal of Steroid Biochemistry
IS - 5
ER -