AM1 AND PM3 TRANSITION STRUCTURE FOR THE HYDRIDE TRANSFER - A MODEL OF REACTION CATALYZED BY DIHYDROFOLATE-REDUCTASE

The transition state structure for the hydride transfer in dihydrofolate reductase, DHFR, enzyme has been calculated with analytical gradients at semiempirical levels: AM 1 and PM3. The geometry, electronic structure and transition vector components are qualitatively semiempirical level independent. Comparing the transition structures for the hydride transfer step in models of liver alcohol dehydrogenase, formate dehydrogenase, lactate dehydrogenase, and glutathione reductase, the geometries of these stationary points are transferable and invariant. The topology of the transition structures in these enzymes resembles the one calculated in this paper.