To start, we might have la look into what a “Virtual Screening” is. For a definition, we could have this one:
Virtual Screening, or “VS” for short, is a computational technique mainly used in the search for bioactive compounds in drug discovery, agrochemistry, phytochemistry, nutraceutricals, cosmetics. It consists in searching in libraries of small molecules in order to identify those structures which are most likely to bind to a usually larger target, typically a protein receptor or enzyme, nucleic acids or some other more complex macromolecules.
Translating this into plain language, it means that we use computers to calculate how well some small chemical molecule fits against, or interacts synergically with other big molecules. Maybe this does not sound like a big thing, but, there is definitely more to it than it seems. It means you can do all of the following (try to find your case!):
Of course, as we are talking about computers, every time we say that we need “a molecule”, we mean that we need “a computer model of a molecule“. This means that we have to build a representation of each of these molecules (most of the times, such representations already existe, and we only have to find them). But this is not everything we can do: these computer models, have to capture the properties of the molecules. We are also able to compare the small molecules we were talking about by their properties.
So, if we know that a molecule is able to do something (like binding to a big molecule) because it has certain properties, we could also think that other molecules with similar properties (structural, electrostatic, pharmacophoric, etc) could do the same. Even if the molecule looks completely different. And we can do that: we can also compare sets of small molecules based on properties as shape, electrostatic charges, polarity, etc. This is what we call “search of non-structural analogues“
And finally, we can “observe” what happens to a molecule over time when we put it in a certain situation. We can do this by making “molecular dynamics” simulations, and these may help us understand processes that happen over time and to elucidate biological mechanisms of action.
Ok. This is what we can do. But, why would we want to do any of that?
It is easy: Figure our “big molecule” is a protein responsible for some disease, and by binding a small molecule you are able to deactivate it, and cure your disease. You have just found a lead on a new drug.
Or, maybe your “big molecule” is an enzyme that is vital for some fungus or insect, and by binding the small molecule you are able to prevent it from growing. Now you have a fungicide, or an insecticide!
Also, it works not only for proteins or enzymes: we can also calculate binding affinities to other kind of molecules, i.e. cyclodextrins, so that we can make calculations for encapsulating smaller compounds, so that, i.e. they turn to be soluble in water.
These are only very basic things we can do, and just some very simple examples. If you are in doubt, or still do not get an idea of how all of this works, Contact us! We will be happy to help you out, and it will also help us to improve this page!