The UV, FTIR and fluorescence spectra differences of glucoamylase in the presence and absence of organic solvent e. g. acetone, methanol, propanol, dioxane, ethylane glycol etc. show that the aromatic amino acid (Trp, Tyr, Phe) are exposed after solvent-perturbation and then the conformational change of glucoamylase may be occurred with fast inactivation of the enzyme.