Protein Concentration Determination using Spectrophotometer

Laboratory Report 1
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Laboratory Report 2
Title: Protein Concentration
Abstract
This experiment aimed at determining the concentration of different samples of proteins.
Different methods are used in the determination of the concentration of protein in solution
samples. In this experiment, a spectrophotometer was used and a calibration curve generated
from the values obtained. The sample solutions illustrated different color changes. The darker the
color the higher the protein concentration in the sample. A line of best fit was generated and the
equation in the form y=mx+c was generated in which y represented the absorbance of the
samples at 595nm.
Aim
To determine the concentration of different samples of proteins using ultraviolet spectroscopy
Introduction
The determination of the concentration of proteins in a sample is a fundamental step when it
comes to any laboratory workflow that revolves around extraction and/ or analysis of proteins.
The knowledge on the amount of proteins contained in a sample is useful in making comparison
of results from one protein yield to another (Buxbaum, 2015, p.178). The knowledge is as well
important in the accurate measurement of the kinetics of enzymes and normalization of various
samples for the purposes of comparison or storage. The choice of an appropriate assay has a
significant role to play when it comes to the determination of the concentration of protein in a
sample (Cote, 2010, p.275).

Laboratory Report 3
Estimation of the concentration of a given protein sample is one of the most commonly tasks
carried out in biochemistry lab. Numerous methods are deployed in the determination of the
concentration of proteins including analysis of the changes in the properties of the spectra in
some dyes in the presence of proteins, analysis of amino acids following hydrolysis of the acid
protein as well as spectrophotometric estimation of the proteins either in far or near UV region
(Kurtz, 2009, p.215).
The main objective in this lab is to come up with the curves for each of the BSA standard
absorbances against the concentration in mg/mL in order to determine the concentration of the
proteins for the unknown samples. Multiple assays can be conducted to determine the
concentration of a protein sample but not all the samples would be appropriate for the specific
data that is required for this lab (Michael, 2011, p.335). Biuret Assay is ideal for proteins that
have low concentration ranging from 5 to 16 mg/mL and uses copper (II) in binding the peptide
bonds thereby turning the solution to violet. The absorption in Biuret Assay is measured at
540nm.
Apparatus
 Standard bovine serum albumin (BSA) solution (1 mg/mL)
 Cuvettes
 1.5 ml centrifuge tubes
 Spectrophotometer (Richard, 2011, p.198)
 Bradford reagent
 Pipettes
 Water