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# How do I use this molar extinction coefficient?

Long story short, we want to be able to use the molar extinction coefficient of a protein to calculate protein concentration instead of constantly having to create a standard curve and calculating from that.

The formula to get the protein concentration is as follows: (A280)(dilution factor) / 51,300 (that’s the extinction coefficient) = protein concentration.

Since it’s the molar extinction coefficient, it’s in these units I’m unfamiliar with in the sense that everything I’m looking up makes me unsure why they rearrange it. Someone said it’s simply “mol/Liter” but I also see “mol/L-1 cm-1” So I’m just confused as to what the units are in the actual equation then.

We then want to convert the answer into mg/mL. That’s the goal here: we want it in mg/mL.

Apparently I have to know the Molecular Weight of this protein, which is 34,620. But I don’t know how to incorporate that into all of this in order to figure this out.

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