## 2 Discussion
### Conclusive Remarks  
The bacterial envelope's outer membrane is a crucial component that is vital in controlling bacterial metabolism and adaptation [7,27,29,37,45]. One of the essential parts of the outer membrane is the outer membrane proteins, which regulate the diffusion of vital nutrients and other solutes across the membrane, thereby influencing bacterial survival and growth [7; 29; 182]. The unique structural and functional properties of outer membrane proteins, such as the constriction region and associated amino acids, may play a crucial role in determining the rate at which solutes diffuse across the bacterial envelope [7; 27; 29; 37; 45; 48]. Outer membrane proteins have been extensively researched for many years, and recent advancements in methodology have provided new insights into the process of antibiotic translocation [15; 29; 30]. Specifically, membrane channels such as HMP-PA [46], Omp-PD [46], Omp-SL [46], HMP-AB [46],/CarO isoforms [155; 157], rOprD homologue [158], OccAB1-OccAB4 [159], DcaP [22], Omp-ECB [46], OmpF and OmpC [24; 26; 38; 39; 44; 48; 51; 52; 53; 55; 56; 74; 75; 76; 81; 82; 83; 84; 87; 89; 90; 95; 96; 97; 98; 99; 102; 104; 105; 106; 107; 109; 110; 111; 112; 113; 114; 115; 116; 117], Omp35, Omp36 [23; 113; 114; 115; 116; 117; 118; 119; 120; 121; 122; 123; 124; 125; 126; 127; 128; 129; 130; 131; 132; 133; 134; 135; 136; 137; 138; 139; 140; 141; 142; 143; 144], OccB3 [42], OccK1, OccK2 [135], Occk8(OprE) [164] have shown a critical role in controlling the membrane's permeability in Gram-negative bacteria [23; 27; 37; 38; 45]. The \(\beta\)-lactam antibiotics have been considered and have significantly received the most attention regarding their translocation across outer membranes [7; 23; 38; 87]. Over the last three decades, many studies have demonstrated the function of membrane transporters/porins in \(\beta\)-lactam uptake/translocation and the underlying characteristics required for uptake/translocation [7; 23; 31; 37; 38; 42; 77]. The effective flux all through the bacterial membrane and different transporters/porins can now be quantified in real-time using innovative techniques such as electrophysiology reversal potential assay, mass spectrometry, and other assays [7; 31; 37; 45; 54]. This has resulted in a better understanding of the structural and functional properties that determine outer membrane permeability and the intracellular concentration of permeating compounds, which ultimately impact bacterial susceptibility [7; 27; 31; 37; 38; 40; 54; 153]. Studies have shown that permeation across porins occurs through passive diffusion for zwitterionic compounds through OmpF [44; 100]. Further, it has been determined that OmpF may have higher permeability rates than OmpC, with the latter's pore interior being more negative, making it more cation selective than OmpF [33; 36; 38; 42; 48]. In conjunction with the current structural determination of many bacterial membrane transporters/porins, numerous studies investigate their structural and physical properties to envisage small molecule translocation [44; 46; 77; 100]. The work employs MS to understand the potential trajectories of small molecules to traverse porins and have produced essential observations [44; 48; 76; 77; 132; 177]. The study of porins using electrophysiology gives a better understanding of the uptake of drugs through different porins, which can be readily measured by changes in ion flux [181; 183]. The example has shown that the ion-current through with the OmpF channel decreases temporarily dependent on pH in the presence of ampicillin molecule, the maximum decrease occurring at the range of pH where ampicillin is zwitterionic [181; 183]. MS suggests that ampicillin may obstructs the OmpF pore by interacting with charged residues of the membrane pore [87]. Similar outcomes were found for amoxicillin, a zwitterionic \(\beta\)-lactam [84; 99; 181; 183]. However, no interaction was observed with carbenicillin, azlocillin, and piperacillin [84; 99; 181; 183].