Measurement of protein using bicinchoninic acid.

Analytical biochemistry (1985-10-01)
P K Smith, R I Krohn, G T Hermanson, A K Mallia, F H Gartner, M D Provenzano, E K Fujimoto, N M Goeke, B J Olson, D C Klenk
ABSTRACT

Bicinchoninic acid, sodium salt, is a stable, water-soluble compound capable of forming an intense purple complex with cuprous ion (Cu1+) in an alkaline environment. This reagent forms the basis of an analytical method capable of monitoring cuprous ion produced in the reaction of protein with alkaline Cu2+ (biuret reaction). The color produced from this reaction is stable and increases in a proportional fashion over a broad range of increasing protein concentrations. When compared to the method of Lowry et al., the results reported here demonstrate a greater tolerance of the bicinchoninate reagent toward such commonly encountered interferences as nonionic detergents and simple buffer salts. The stability of the reagent and resulting chromophore also allows for a simplified, one-step analysis and an enhanced flexibility in protocol selection. This new method maintains the high sensitivity and low protein-to-protein variation associated with the Lowry technique.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Bicinchoninic Acid Kit for Protein Determination, for 200-1000 μg/ml protein
Supelco
Bicinchoninic Acid solution
Sigma-Aldrich
Bicinchoninic acid disodium salt hydrate, ≥98% (HPLC)