6 research outputs found
Enumeration, conformation sampling and population of libraries of peptide macrocycles for the search of chemotherapeutic cardioprotection agents
Peptides are uniquely endowed with features that allow them to perturb previously difficult to drug biomolecular targets. Peptide macrocycles in particular have seen a flurry of recent interest due to their enhanced bioavailability, tunability and specificity. Although these properties make them attractive hit-candidates in early stage drug discovery, knowing which peptides to pursue is nonâtrivial due to the magnitude of the peptide sequence space. Computational screening approaches show promise in their ability to address the size of this search space but suffer from their inability to accurately interrogate the conformational landscape of peptide macrocycles. We developed an inâsilico compound enumerator that was tasked with populating a conformationally laden peptide virtual library. This library was then used in the search for cardioâprotective agents (that may be administered, reducing tissue damage during reperfusion after ischemia (heart attacks)). Our enumerator successfully generated a library of 15.2 billion compounds, requiring the use of compression algorithms, conformational sampling protocols and management of aggregated compute resources in the context of a local cluster. In the absence of experimental biophysical data, we performed biased sampling during alchemical molecular dynamics simulations in order to observe cyclophilinâD perturbation by cyclosporine A and its mitochondrial targeted analogue. Reliable intermediate state averaging through a WHAM analysis of the biased dynamic pulling simulations confirmed that the cardioâprotective activity of cyclosporine A was due to its mitochondrial targeting. Paralleltempered solution molecular dynamics in combination with efficient clustering isolated the essential dynamics of a cyclic peptide scaffold. The rapid enumeration of skeletons from these essential dynamics gave rise to a conformation laden virtual library of all the 15.2 Billion unique cyclic peptides (given the limits on peptide sequence imposed). Analysis of this library showed the exact extent of physicochemical properties covered, relative to the bare scaffold precursor. Molecular docking of a subset of the virtual library against cyclophilinâD showed significant improvements in affinity to the target (relative to cyclosporine A). The conformation laden virtual library, accessed by our methodology, provided derivatives that were able to make many interactions per peptide with the cyclophilinâD target. Machine learning methods showed promise in the training of Support Vector Machines for synthetic feasibility prediction for this library. The synergy between enumeration and conformational sampling greatly improves the performance of this library during virtual screening, even when only a subset is used
Prédictions de complexes protéine-ligand par arrimage moléculaire : développement et applications
Les protĂ©ines sont des entitĂ©s intrinsĂšquement dynamiques et de nombreuses Ă©tudes ont dĂ©montrĂ© lâimportance de cette propriĂ©tĂ© Ă leurs fonctions. Plus particuliĂšrement, la flexibilitĂ© protĂ©ique est essentielle dans le processus de reconnaissance molĂ©culaire. Lors de tels Ă©vĂšnements, les protĂ©ines peuvent subir des changements conformationnels mineurs (dĂ©placement de chaĂźnes latĂ©rales des acides aminĂ©s), majeurs (dĂ©placement de domaines entiers de la protĂ©ine) et/ou mĂȘme se replier. Mes travaux de thĂšse ont permis de dĂ©montrer que de tels rĂ©arrangements mineurs sont frĂ©quents et ont aussi permis dâĂ©lucider certaines causes potentielles physiques et chimiques. De plus, mes travaux ont dĂ©montrĂ© lâimportance de considĂ©rer la flexibilitĂ© des chaĂźnes latĂ©rales lors de simulations de tels Ă©vĂšnements de reconnaissance molĂ©culaire.
Plusieurs mĂ©thodes computationnelles, dont la dynamique molĂ©culaire et lâarrimage molĂ©culaire, peuvent ĂȘtre utilisĂ©es pour prĂ©dire la liaison dâun ligand Ă sa cible. Dâun cĂŽtĂ©, la dynamique molĂ©culaire permet de considĂ©rer la flexibilitĂ© protĂ©ique Ă toute Ă©chelle, mais nĂ©cessite un pouvoir computationnel Ă©norme. Dâun autre cĂŽtĂ©, lâarrimage molĂ©culaire restreint le nombre de degrĂ©s de libertĂ© considĂ©rĂ©s, entre autres imposĂ©s par la flexibilitĂ© protĂ©ique. Mes travaux de thĂšse, en ce qui a attrait au dĂ©veloppement de la mĂ©thode dâarrimage molĂ©culaire appelĂ©e FlexAID, ont permis dâinclure une certaine flexibilitĂ© protĂ©ique intrinsĂšque limitant ainsi le nombre de degrĂ©s de libertĂ© requis, tout en offrant la possibilitĂ© dâajouter des degrĂ©s de libertĂ© supplĂ©mentaire pour les mouvements de plus grande envergure ne pouvant ĂȘtre accommodĂ©s par cette plasticitĂ© protĂ©ique. De plus, mes travaux dĂ©montrent que FlexAID est compĂ©titive aux autres mĂ©thodes dans le domaine et obtient de meilleures performances dans le scĂ©nario oĂč les conformations des protĂ©ines sous la forme liĂ©e sont inconnues.
Dans un autre ordre dâidĂ©es, les nombreuses simplifications introduites par un logiciel dâarrimage lui permettent dâĂȘtre une mĂ©thode rapide et applicable Ă la dĂ©couverte de nouvelles molĂ©cules ayant un effet thĂ©rapeutique potentiel. Lorsquâune mĂ©thode de repointage est utilisĂ©e, les rĂ©sultats de FlexAID en enrichissement de composĂ©s se rapprochent des performances dâautres logiciels couramment utilisĂ©s lors de criblage virtuel. Mes travaux portant sur le systĂšme biologique de la Matriptase-2 montrent que la mĂ©thode FlexAID peut ĂȘtre utilisĂ©e Ă la dĂ©couverte de nouvelles petites molĂ©cules