Methods for obtaining highly target-specific inhibitory compounds are disclosed. These inhibitory compounds provide for the preservation of a native, non-activated form of an autoinhibited molecule, such as a protein or enzyme. The inhibitory compounds are further described as essentially free of inhibitory activity for non-native forms of an autoinhibited molecule of interest. By way of example, such autoinhibited molecules of interest include proteins and enzymes, such as the p-21-activated kinases (Paks) and the Rho-activated proteins. The inhibitory compounds act by binding to a distinct, autoinhibitory domain of an autoinhibited molecule (protein), and thereby stabilize an autoinhibited conformation of the molecule (protein). Preparations, including pharmaceutical preparations, compromising a composition enriched for the inhibitory compounds are also disclosed.