Protein Purification from Corn Germ Danielle McConnell Department of Chemical Engineering Iowa State University

Why extract Protein X from Transgenic Corn? Could be a good alternative for a low calorie sweetener 9500 times sweeter than sucrose on a molecular basis Good extraction attributes (heat- stable and low molecular weight) Transgenic corn is economically feasible, easy to scale up, and is highly available

Extraction (part 1) pH determination Isoelectric point of Protein is 5.72 Tested pHs 4,5,6, and 7 Total Protein Assays pH 4 showed the least amount of total protein extracted

Extraction (part 2) Determination of Heating Time At 80 ° C Protein is thermo-stable Total Protein Assays of precipitate at different times At ten minutes the total protein is the smallest

Cation Exchange Chromatography Proteins bind to the negatively charged clusters by electrostatic forces A SP-Sepharose column was used to run the ion exchange According to the chromatogram (see next panel), peak 6 or fraction #38 displays the protein rich sample Cation Exchange Setup shown above

Cation Exchange Chromatogram Conductivity vs. Time (fraction # at top of graph)

Ultrafiltration Used a used large and small molecular weight cutoff membranes to filter the extract Protein should be left in the retentate of the small MW cutoff membrane Total Protein Assays gave a preliminary evaluation of what was left in the retentate

Ultrafiltration Flowchart

Reverse Phase HPLC Detects purity of Protein from injected sample Concentration can be found by integrating the peak area Protein X typically elutes around 15 minutes The HPLC chromatogram displays three elutions. The red line indicates a pure protein sample, the blue line represents pure protein from the cation exchange, and the black line portrays a sample of extract with spiked protein.

HPLC Chromatogram mV vs. Minutes

Final Discussion: The final results of this project have not been determined, however, many progressive steps have been made in obtaining the protein from corn germ. Various extraction conditions (pH and salt conditions), filtration steps, and analysis of a quantification method (ELISA tests) are currently being researched to obtain a purified protein. The final steps of the protein sequence will be based on a combination of factors such as purity and yield which will be tested by reverse phase HPLC and the ELISA test. Diagram of complete Antibody setup for ELISA testing

Acknowledgments: An extended gratification and thank you is made to the multitude of people who not only made this project possible but successful: Dr. Charles Glatz PWSE Yandi Dharmadi, Zhengrong Gu, Maureen Griffin, Todd Menkhaus, and Jim Kupferschmit