Comparative quantitative structure-activity relationship database development

Methods to predict the hydrolysis rates of organic compounds for use in the environmental assessment of pollutants have not advanced significantly since the first edition of the Lyman Handbook (Lyman et al., 1982). Two approaches have been used extensively to obtain estimates of hydrolytic rate constants for use in environmental systems. The first and potentially more precise method is to apply quantitative structure/activity relationships (QSARs). To develop such predictive methods, one needs a set of rate constants for a series of compounds that have systematic variations in structure and a database of molecular descriptors related to the substituents on the reactant molecule. The second and more widely used method is to compare the target compound with an analogous compound or compounds containing similar functional groups and structure, to obtain a less quantitative estimate of the rate constant. 

With protein structures, we can observe similarities in topology or even in structural details. Comparison of protein structures can reveal distant evolutionary relationships that would not be detected by sequence aligmnent alone. Comparing and overlapping two protein stractures quantitatively remain an active area of development in structural biochemistry. Methods for protein comparison generally rely on a fast full search of the protein structure database. 

---