An AM1 study on the electron-donating and electron-accepting character of biomolecules

Energy of the highest occupied molecular orbital (E-HOMO) and energy of the lowest unoccupied molecular orbital (E-LUMO) are very often related to the electron-donating (E-HOMO) and electron-accepting (E-LUMO) character of a molecule. In this work AM1 calculations for the E-HOMO and E-LUMO of 15 biomolecules are performed with the aim to obtain a scale for the electron-donating and electron-accepting character of biomolecules, as they can interact in the biological environment through a charge-transfer mechanism. From the E-HOMO and E-LUMO values obtained with the AM1 serniempirical method, we were able to classify the 15 compounds studied into four groups: A (good electron-donor molecules), B (good electron-acceptor molecules), C (moderate electron-donor molecules), and D (compounds that behave as both electron-donor and electron-acceptor molecules). (C) 2003 Wiley Periodicals, Inc.