Geldanamycin, an HSP90 inhibitor (Kd: 1.2 μM), specifically disrupts glucocorticoid receptor (GR)/HSP association.

HSP90 (N-terminal domain):0.78 μM(Kd), HSP90:1.2 μM(Kd), p185:70 nM

Geldanamycin通过与Hsp90s N-末端结构域（残基1-220）中的ATP结合位点结合，剂量依赖性地抑制Hsp90的ATP酶活性。[1] 在A2780人类卵巢细胞系中，Geldanamycin引起剂量依赖的G2阶段阻滞和S期进入的可逆抑制，该抑制伴随p53的增加，并最终证明是依赖于p53的。[2] Geldanamycin导致p185受体蛋白酪氨酸激酶的多泛素化和蛋白酶体降解，显示出70 nM的IC50。[3, 4] 作为典型的抗肿瘤试剂，Geldanamycin对60种人类肿瘤细胞系的平均GI50为0.18 μM。[5]

Geldanamycin（50 mg/kg）在FRE/erbB-2小鼠中对pl85相关的磷酸化酪氨酸水平显示出30%的抑制作用。[6]

Isothermal Titration Calorimetry (ITC) of Nucelotide Binding: The titration experiments are performed using the MSC system. In each experiment, 16 aliquots of 15 μL of geldanamycin (300 μM in 1% DMSO) are injected into 1.3 mL of protein (31 μM in 20 mMTris-HCl, pH 7.5, 1 mMEDTA) at 25 °C, and the resulting data are fit after subtracting the heats of dilution. Heats of dilution are determined in separate experiments from addition of geldanamycin into buffer and buffer into protein. No evidence for binding of DMSO in the nucleotide binding site is observed. Titration data are fit using a nonlinear least-squares curve-fitting algorithm with three floating variables: stoichiometry, binding constant (Kb) 1/Kd), and change of enthalpy of interaction (ΔH°). Dissociation constants estimated for geldanamycin binding to intact yeast Hsp90 is 1.22 μM, and for binding to Hsp90 N-terminal domain is 0.78 μM. No meaningful heat is observed with binding to the C-terminal fragment.

Exponentially growing cells are treated with Geldanamycin and at various times DNA synthesis is assessed by incorporation of bromodeoxyuridine (BrdUrd) and flow cytometric analysis. No marked difference in total cell number is noted during this time course for treated and untreated cultures. BrdUrd (10 μM) is incorporated over a 4-h incubation period at 37 °C and cells are harvested and fixed in 70% ethanol. After denaturation of the DNA with 2 N HC1, cells are incubated with an anti-BrdUrd mouse monoclonal antibody followed by a fluorescein isothiocyanate (FITC)-linked goat anti-mouse IgG. Cells are stained for 30 minutes at room temperature with propidium iodide and analysed by flow cytometry using a Coulter EPICS Profile Analyzer. (Only for Reference)