1. To prepare a standard curve of absorbance versus protein concentration by using Bovine Serum Albumin (BSA).
2. To determine BSA concentration in two sample solutions.
3. To determine protein concentration in apple juice.
Introduction
What is Bradford protein assay? The Bradford protein assay is a spectroscopic analytical procedure used to measure the concentration of protein in a solution [1]. There are several reagents that can be used to determine the concentration of protein in solution which are Bradford reagent, Biuret reagent, Lowry protein assay and many more. In this experiment, the Bradford Reagent is used to measure the protein concentration. Marion M. Bradford had developed the Bradford protein assay. The Bradford assay is a colorimetric assay based on the interaction between Coomassie brilliant blue and the arginine and aromatic residues in your protein. When the dye binds to these residues, its maximum absorption shifts from 470 nm to 595 nm [2]. Basically the absorbance of a series concentrations of BSA is obtained by using spectrophotometer, and the graph is plotted then a standard curve is drawn. BSA stands for Bovine serum albumin which is a serum albumin protein derived from cows. It is often used as a protein concentration standard in lab experiments. The nickname of BSA is "Fraction V" refers to albumin being the fifth fraction of the original Edwin Cohn purification methodology that made use of differential solubility characteristics of plasma proteins [3].
Figure 1 Albumin [3] There are several biochemical applications that BSA has been used. The most well-known applications are ELISAs (Enzyme-Linked Immunosorbent Assay), immunoblots, and immunohistochemistry [3].
Apparatus and Material
Bradford Reagent, bovine serum albumin (BSA), distilled water, apple juice sample, unknown sample of A, unknown sample of B, 8 test tubes, 2