Purity ~99%. Semi-synthetic derivative of geldanamycin, demonstrating greater stability and lower in vivo toxicity than its parent compound. 17-AAG binds specifically to heat shock protein Hsp90 in a manner similar to geldanamycin, but the binding is weaker. Solubility: Soluble in DMSO at 150mg/ml; soluble in ethanol at 5mg/ml; very poorly soluble in water; maximum solubility in plain water is estimated to be about 20-50uM; buffers, serum, or other additives may increase or decrease the aqueous solubility.