Spectroscopic analysis and docking simulation on the recognition and binding of TEM-1 β-lactamase with β-lactam antibiotics

The interaction between TEM-1 β-lactamase and Antibiotics is very important in the hydrolysis of Antibiotics. In the present study, the recognition and binding of TEM-1 β-lactamase with three β-lactam Antibiotics, including penicillin G, cefalexin and cefoxitin, was investigated by fluorescence and ultraviolet-visible absorption spectra in combination with molecular docking in the temperature range of 278-288 K and under simulated physiological conditions. The results demonstrated that the fluorescence emissions of TEM-1 β-lactamase were extinguished by static quenching and the energy of TEM-1 β-lactamase was transferred in a non-radioactive manner. The binding of TEM-1 β-lactamase with the three Antibiotics was a spontaneously exothermic process, with binding constants of 1.41×10⁷, 7.81×10⁶ and 5.43×10⁴ at 278 K. Furthermore, binding was driven by enthalpy change and the binding forces between them were mainly hydrogen bonding and Van der Waals forces. A TEM-1 β-lactamase only bound with one Antibiotic at a time and the binding capacity between them was closely associated with the functional groups and flexibility in the Antibiotics. In addition, a conformational change occurred in the TEM-1 β-lactamases when they bound with the three Antibiotics and TEM-1 β-lactamase-antibiotic complexes were formed. The present study provided an insight into the recognition and binding of TEM-1 β-lactamase with β-lactam Antibiotics, which may be helpful for designing a novel substrate for TEM-1 β-lactamase and developing novel Antibiotics that are resistant to the Enzyme.