Biology: Separation of Proteins

Lab Report 1: Separation of Proteins





Abstract/Summary:   “Proteins account for more than 50% of the dry weight of most cells, and they are instrumental in almost everything organisms do” (Campbell, 1999).   The significance of proteins to the continuation of our biological systems is undeniable, and a study of how to quantify proteins seems an appropriate introduction to our studies of biology.   In order to study proteins we must first know how to separate then quantify the amount using basic principles of experimental design such as a standard curve.   In this experiment we wish to quantify the amount of previously extracted protein by measuring the absorbance of the unknown amount and determining its concentration by overlaying it against a standard curve of the absorbance of known concentrations of the protein.   We used the dye agent Bradford Protein Assay to get an absorbance of 0.078, 0.143, 0.393, 0.473, and 0.527 at the protein’s respective concentrations of 0.28, 0.56, 0.84, 1.12, and 1.40 mg/mL.   When a best-fit line was applied to the standard curve, and the absorbance of our unknown concentration (0.317 A) plotted, we estimated a concentration of around 0.84 mg/mL of protein.   Our calculations indicated a quantity of 168 mg of protein, which was an approximately 8.96% yield of the projected 1875 mg that was expected.   Errors that may have led to this small yield percentage may have stemmed from our previous lab and our initial attempts to extract the desired amount of protein.





Introduction:   Within this experiment we wish to facilitate a greater understanding of the concepts of experimental design and quantifying techniques.   Specifically, this lab will allow us to gain an enhanced understanding of the isolation of a protein using differential solubility, which allows us to separate and purify various proteins using high concentrations of a specific salt so that they may be studied in great detail....