COMPARATIVE MOLECULAR-FIELD ANALYSIS (COMFA) OF MX COMPOUNDS USING DIFFERENT SEMIEMPIRICAL METHODS - LUMO FIELD AND ITS CORRELATION WITH MUTAGENIC ACTIVITY

In the present paper we make a comparison among three different semi-e mpirical methods (AM1, MNDO and PM3) for the optimization of the geome tries and calculation of different properties of MX compounds. The res ults were used to develop a CoMFA model to correlate the TA100 mutagen icity of these compounds with the LUMO field. The correlations between the LUMO field and steric, electrostatic and CoMFA fields generated a utomatically by the SYBYL CoMFA program, were explored. A comparison a mong different values of grid spacing for the lattice and standard dev iation thresholds for column filtering was carried out to select the b est values for this and future work. The results indicate that AM1 and PM3 methods represent a real improvement over MNDO in respect to QSAR studies relating electronic properties and mutagenicity for these com pounds.