# What is the activity of 1X Trypsin solutions? - (Sep/09/2012 )

Hi there,

when googleing I can either find the activity of 1 mg Trypsin, which seems to be around 150 - 180 units (TAME) which is around 3000 - 3500 USP, or I find things like this: "1X Trypsin-EDTA 1:250, 0.25% (w/v) solution".

How would I calculate the activity of trypsin in a 1X solution?

Thank you very much.

-Johannes-

You could work out the conversion using 0.25%=mg/ml...

-bob1-

alright, I got a little further in my research.

Turns out that "Trypsin 1:250" simply means "trypsin with an activity of 250 USP/mg".

That means a 1 liter 0.25% 1X solution contains 2500 mg Trypsin 1:250

That would make a total activity of: 2500 mg * 250 USP/mg = 625000 USP/L or 625 USP/mL

That means if i wanted to make a 1X 0.25% solution with the Trypsin I have here (~4000 USP) I would need 625000 / 400 =156.25 mg

-Johannes-

We just use 250 mg of trypsin per litre for cell culture work. Unless you are doing some sort of enzymatic assays, the activity won't matter too much.

-bob1-