Electronic structure of testosterone: A semiempirical and ab initio assessment

✍ Scribed by Carlos Kubli-Garfias

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 335 KB
• Volume: 62
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1997)62:3<279::aid-qua6>3.0.co;2-t

✦ Synopsis

Testosterone 17␤-hydroxy-4-androsten-3-one was studied by the semiempirical AM1 and PM3 and ab initio STO-3G*, 3-21G*, and 6-31G* methods. The goals were to compare those methods and to know the electronic structure of the hormone. Full Ž . geometry optimization was performed, and two crystal conformers T1 and T2 , and experimental dipole moment in solution were used for comparison. One conformer with a dipole moment similar to the solvated conditions was generated. Total energy, entalphies, dipole moments, charges, electrostatic potentials, and highest occupied Ž . Ž . molecular orbitals HOMO and lowest unoccupied molecular orbital LUMO were Ž . calculated. Root-mean-square RMS index of the theoretical molecules against T1 and T2 showed best results with the 3-21G* and 6-31G* methods, while AM1 gave better energies than PM3. Dipole moments were directed toward the OH group and the botton face of the A ring. The frontier orbitals were located along the C4᎐C5 bond, particularly the LUMO was split between C4 and C5, predicting the action of enzymes at C5 yielding to 5␣ and 5␤-reduced androgens. Electrostatic potentials might be also of biological importance since they are coincidental with the dipole-moment orientation. Finally, it is interesting that the solvatedlike conformer, its properties, and the OH group laid between the same group of T1 and T2 and with a total energy between the crystals and the gas phase or in vacuo conditions. This results might also explain the biology of testosterone and use them to model the hormone᎐receptor interaction.