Membrane-Bound Transcription Factor Site-1 Protease in PF429242 Bound State: Computational Kinetics and Dynamics of Reversible Binding.

Membrane-bound transcription factor site-1 protease (S1P) is an emerging clinical target due to its roles in lipogenesis, lysosomal biogenesis, unfolded protein response and viral glycoprotein processing. In this study, homology model of S1P was created in order to understand the structural basis for S1P inhibition by PF429242 using molecular docking, molecular dynamics simulation and in silico kinetics studies. PF429242 was docked (GlideScorePF429242=-5.20 kcal/mol) into the catalytic triad (D218, H249 and S414) and validated (R2=0.5686). The reversible binding kinetic parameter (Koff/Kon) was estimated at=7.28E-03 M with fully bound and apo-states interspersed by 3 transient ligand-bound states with unique binding signatures; water plays a major role in PF429242 dissociation from the catalytic site. Communication between key catalytic triad residues is altered in the presence of PF429242. In apo-S1P state, S414-S307/V216-D218 is the preferred route but in PF429242-bound state, S414-S417/V216-D218 is preferred. Communication between S414 and H249 is also shortened in PF429242 bound state; here, only L410 is required unlike apo-state, which requires P418, V256 and F252. Ligand binding did not alter the communication route between S414 and H249 as both recruited D244 and G220. In conclusion, PF429242 binds tightly but reversible to S1P and the details of this interaction has been presented to guide future efforts at developing novel inhibitors. Site-1-protease; PF429242; Kon/Koff; Network analysis.

Salient Aspects of PBP2A-inhibition; A QSAR Study.

BACKGROUND: Inhibition of penicillin binding protein 2A (PBP2A) represents a sound drug design strategy in combatting Methicillin resistant Staphylococcus aureus (MRSA). Considering the urgent need for effective antimicrobials in combatting MRSA infections, we have developed a statistically robust ensemble of molecular descriptors (1, 2, & 3-D) from compounds targeting PBP2A in vivo. METHODS: 37 (training set: 26, test set: 11) PBP2A-inhibitors were submitted for descriptor generation after which an unsupervised, non-exhaustive genetic algorithm (GA) was deployed for fishing out the best descriptor subset. Assignment of descriptors to a regression model was accomplished with the Partial Least Square (PLS) algorithm. At the end, an ensemble of 30 descriptors accurately predicted the ligand bioactivity, IC50 (R = 0.9996, R2 = 0.9992, R2 a = 0.9949, SEE =, 0.2297 Q2 LOO = 0.9741). RESULTS AND CONCLUSION: Inferentially, we noticed that the overall efficacy of this model greatly depends on atomic polarizability and negative charge (electron) density. Besides the formula derived, the high dimensional model also offers critical insights into salient cheminformatics parameter to note during hit-to-lead PBP2A-antagonist optimization.

Agemone mexicana flavanones; apposite inverse agonists of the ß2-adrenergic receptor in asthma treatment.

Asthma is an inflammatory disease of the airway that poses a major threat to human health. With increase industrialization in the developed and developing countries, the incidence of asthma is on the rise. The ß2-adrenergic receptor is an important target in designing anti-asthmatic drugs. The synthetic agonists of the ß2-adrenergic receptor used over the years proved effective, but with indispensable side effects, thereby limiting their therapeutic use on a long-term scale. Inverse agonists of this receptor, although initially contraindicated, had been reported to have long-term beneficial effects. Phytochemicals from Agemone mexicana were screened against the human ß2-adrenergic receptor in the agonist, inverse agonist, covalent agonist, and the antagonist conformations. Molecular docking of the phyto-constituents showed that the plant constituents bind better to the inverse agonist bound conformation of the protein, and revealed two flavanones; eriodictyol and hesperitin, with lower free energy (ΔG) values and higher affinities to the inverse agonist bound receptor than the co-crystallized ligand. Eriodictyol and hesperitin bind with the glide score of -10.684 and - 9.958 kcal/mol respectively, while the standard compound ICI-118551, binds with glide score of -9.503 kcal/mol. Further interaction profiling at the protein orthosteric site and ADME/Tox screening confirmed the drug-like properties of these compounds.

Molecular docking analysis of phyto-constituents from Cannabis sativa with pfDHFR.

Available antimalarial drugs have been associated with numerous side effects, which include skin rashes and myelo-suppression. Therefore, it is of interest to explore compounds from natural source having drug-like properties without side effect. This study focuses on the screening of compounds from Cannabis sativa against malaria Plasmodium falciparum dihydrofolate reductase for antimalarial properties using Glide (Schrodinger maestro 2018-1). The result showed that phytochemicals from Cannabis sativa binds with a higher affinity and lower free energy than the standard ligand with isovitexin and vitexin having a glide score of -11.485 and -10.601 respectively, sophoroside has a glide score of -9.711 which is lower than the cycloguanil (co-crystallized ligand) having a glide score of -6.908. This result gives new perception to the use of Cannabis sativa as antimicrobial agent.