I feel this is a very basic question, but I'd like to have some clarification from dear experts on this.
I've been looking into GST activity in literature to compare them with my results, and coming across different units.
As far as I checked, typically GST assay gives GST activity in umol/mL/min (and so does my protocol).
However, I noticed that some literature reports it in nM/min/mg protein.
I was not sure if they know the protein concentration of reaction mix (which seems to be the case), why they did not just do nmol/min/mg protein or pmol/min/mg protein?
I believe nM/min/mg protein can be converted to nmol/mL/min/mg protein, but would that be essentially equivalent to nmol/min/mg protein (without 'mL'), and that's just variation in how they are expressed? Or am I missing something?
I'd be very grateful for your help.
Thank you!
Often papers are looking for GST activity in relation to detoxification or survival against xenobiotics or other toxins. This means looking at the activity in crude homogenates or body fluids in which the quantities of various GST proteins have not been quantified. When a specific GST protein has been expressed and purified so that the exact quantities are known then activity in relation to the amount of the protein can be made. Or are you asking about normalization for sample concentrations using total protein? In that case a Bradford or BCA assay would have to be done on the sample to identify the quantity of protein/volume so that the value can be divided from the GST activity.
Robert Adolf Brinzer Thank you for your input.
Yes, I was asking about the total protein content. In this specific paper I was looking into (link attached), they mentioned that the Bradford assay was performed to determine the protein concentration so I assumed that was done for both the microsome and cytosol used for EROD and GST assays, respectively.
I see they normalized the unit for EROD (pmol/min/mg protein) but used nM/min/mg protein for GST, where I was confused.
If I convert that to nmol/mL/min/mg protein by dividing the original values by 1000, would that basically mean the same as nmol/min/mg protein?
Article Phase I and II liver enzyme activities in juvenile alligator...
you will be wanting to eliminate the volume variable. From your protein assay you will have your sample concentration in mg protein/mL so your formula becomes nmol/mL/min x ml/mg protein which will cancel out the mL value.
1 pmol is a thousandth of a nmol.
- Badges
- Science topic
- Similar topics
- Counseling Psychology
- Confusion