How to convert the OD of protein to its concentration? - (Aug/04/2006 )

I got the ODs of proteins, but they are out of standard range. So, I want to convert its OD to concentration manually, should I times 50 or 40 to protein OD? What is the unit?

well, please understand that it's not as accurate and will only give you a rough idea, but can't you take the slope of the curve from the standards and extrapolate?

sounds tricky to extrapolate.
You'd better re-do the concentration determination and dilute more your sample.

Let's assume the maximun of your standard is 1 mg/mL, when I use bradford reagent, 1 mg/mL already starts to saturate. It means that 2 mg/mL doesn't give twice OD of 1 mg/mL. If you're protein is very concentrated, you will under-estimate its concentration.