Tuesday, June 12, 2012

Did you know all of the different ways protein concentration can be measured on a microplate reader?

The following table lists all of the relevant methods to determine protein concentration using a microplate reader:


Assay Detection Mode Wavelengths Comments
A280 nm Absorbance 280 nm Use Beer’s Law , molar absorptivity coefficients. No standard curve needed. 
Approx. protein range: 50 – 2000 mg/mL.
Lowry
(Cupric sulfate-tartrate) 
Absorbance 750 nm Compare to a standard curve.
Approx. protein range: 1.0 mg/mL - 1500 mg/mL.
BCA
(Bicinchoninic Acid)
Absorbance 560 (ref 750) nm Compare to a standard curve.
Approx. protein range: 0.5 - 1500 mg/mL.
Bradford
(Coomassie)
Absorbance 595 nm Compare to a standard curve.
Approx. protein range: 1.0 - 1500 mg/mL.
Ninhydrin Absorbance 575 nm Compare to a standard curve.
Approx. protein range: 1.0 - 100 mg/mL.
NanoOrange® Fluorescence 485/570 nm (ex/em) Compare to a standard curve.
Approx. protein range: 0.01 - 10 mg/mL.
Fluorescamine Fluorescence 380/470 nm (ex/em) Compare to a standard curve.
Approx. protein range: 0.1 - 500 mg/mL.
OPA (Ortho-phthalaldehyde ) Fluorescence 340/450 nm (ex/em) Compare to a standard curve.
Approx. protein range: 1.0 - 500 mg/mL.


For a list of application notes that explain various methods of measuring DNA, RNA and Protein using BMG LABTECH microplate readers, visit: http://www.bmglabtech.com/application-notes/molecular-biology/list.cfm?assaycategory_id=5#1

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