Calculating protein concentration - (Jul/27/2007 )

Hi,
I’ve got a question for you:
If you have cells in a T225 that secrete 100ug of protein into 25ml of solution, then that 5ug/ml of protein, right?
If 5ml of this solution is then added to cells in a T25, then the concentration of protein is still 5ug/ml, yes?
But assuming for arguments sake 1cell occupies 1cm2 of space, then those cell in a T25 are actually exposed to 5ug/cell while those in a T225 are exposed to 0.44ug/cell. Can this be right? Can using the same concentration of protein, but having cells in T25 rather than a T225 potentially affect the cells differently?

Most papers I’ve read have inhibitor or agonists expressed as uM solutions (i.e. a concentration), they don’t always mention how many cells or how much volume of the drug was used. Is this wrong or right?


What do you think, my brains is melting

Concentration was the same; the total amount was different because the volume of medium added was not adjusted to per unit of surface area. If you use a saturated concentration of a ligand to begin with, the volume issue is secondary.

I understand that, but i'm still having problems imagining this in my head.

The basic concept/question is would it make a difference to the same number of cells being exposed to 2ml of a 1mg/ml growth factor compared to 1ml of a 2mg/ml growth factor? Both of them have 2mg of growth factor in them.

They are the conentration and amount of protein to add to target cells


I basically have some conditioned media containing some growth factor. I'm trying to determine if it would make a difference if i concentrated this down to a 1mg/ml solution (just for arguments sake -i know this is not reaalistic) and used 5ml on this my target cells or concentrated it down to a 5mg/ml solution and used 1ml on my target cells.


Assuming the flask/well can contain either volumes of solution, could i expect to see a difference in response? Both would contain the same amount of growth factor, but one would be more concentrated

"If you have cells in a T225 that secrete 100ug of protein into 25ml of solution, then that 5ug/ml of protein, right?"
No, that would make 4ug/mL of protein.