In this study, the resonant recognition model (RRM), was developed to locate the so called 'lead-in regions ' or residues that contribute to the creation of the environment that enables proteins to perform their complex functions. The RRM is a physical and mathematical model and provides a significant correlation between spectra of numerical presentation of amino acids and their biological activity. We developed a preliminary model for this purpose and applied it on two well characterized classes of enzymes viz., human proteases and kinases. The results obtained (positions of 'lead-in residues' in the primary structure of the proteins) were used in association with the 3D-structure data of the proteins for the purpose of predicting the catalytic residue of the enzyme. © 2007 IEEE.