After researching the definition of Assay, I am left with the idea that an assay
ID: 32766 • Letter: A
Question
After researching the definition of Assay, I am left with the idea that an assay refers to scientific screening. It could be of chemicals, microbes, etc.
I understand that during drug-discovery assays scientists screen for chemical compounds that may make up an effective drug.
But could someone explain, or provide me with some links that further discuss the process of assays, or how they work or take place during drug discovery? Frankly, I'm also still a bit confused about the definition of "Assay" itself.
Thank you.
Explanation / Answer
An assay may be thought of as a trial or test that is designed to quantitatively determine the amount of a substance in a sample.
Thus a biochemist might use a protein assay to quantitatively determine the amount of protein in a sample, or a pharmacologist might assay a sample to quantitatively determine the amount of drug present, or an enzymologist might carry out an enzyme assay to determine the amount of enzyme activity in a sample.
Let's take the case of the enzymologist. I take a liver sample, homogenize it, centrifuge and take the supernatant (soluble) fraction. I want to quantitatively determine the amount of a given enzyme activity.
I do this by performing a test by (say) adding a sample of the supernatant to a cocktail that 'does something' only if the enzyme of interest is present. The 'do something' could be a color change, where the cocktail contains everything needed for the enzyme to work (all substrates, cofactors etc) and where the enzyme transforms one of the substrates to a coloured product. I now have an enzyme assay which tells me if the enzyme is present (the trial), which may be made quantitative with reference to the amount of color produced in a given time.