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

-SARESK-

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.

-genehunter-1-

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.

-SARESK-

QUOTE (SARESK @ Jul 27 2007, 05:47 PM)
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.

are your concentrations stock solutions to add to cells or working concentrations?

-The Bearer-

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

-SARESK-

"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.

-boquinha-