The principle of the bicinchoninic acid (BCA) assay is similar to the Lowry procedure, in that both rely on the formation of a Cu2+-protein complex under alkaline conditions, followed by reduction of the Cu2+ to Cu1+. The amount of reduction is proportional to the protein present. In the second step, BCA forms a purple colored complex with Cu+1, which is detectable at 562 nm.

Protein + Cu2+ => Cu1+ + BCA => Cu1+- BCA complex

It has been shown that cysteine, cystosine, tryptophan, tyrosine, and the peptide bond are able to reduce Cu2+ to Cu1+. BCA forms a purple-blue complex with Cu1+ in alkaline environments, thus providing a basis to monitor the reduction of alkaline Cu2+ by proteins at absorbance maximum 562 nm.

SPECIAL FEATURES

• Simple and sensitive in protein assays.
  
• Faster and easier than Lowry protein assay.
  
• Compatible with many ionic and nonionic detergents.
  
• Independent of specific amino acid content of proteins.
  
• Accurate over a wide range of protein concentrations.
  

KIT CONTENTS

• BCA Protein Assay Reagent 1: 750ml
  
• BCA Protein Assay Reagent 2: 25ml
  
• Protein Standard Solution: 10ml