Can I Make Yogurt In That?
Over the past few weeks of SURF, I have been working to purify a protein. Sounds dull? It may be pretty repetitive and tedious but it’s certainly far from boring.
Before I could purify my protein I first had to grow the E.Coli cells. A tons of them. Actually 10 liters of culture. Like I explained before, we first have to grow the E.Coli cells into which we inserted the protein before we can extract it. The first step, therefore, was to use this giant machine called a fermentor to grow the cells in a relatively short period of time. And sadly no I can’t make yogurt in it…..
Here it is! 10 liters of broth full of antibiotic resistant E.Coli cells. All this for only 100 milligrams of protein. Pretty ridiculous right?
Throughout the day, I had to monitor the air flow, pH, and other parameters to make sure the E.Coli grew up properly. As you may expect, E.Coli being a bacteria has a rather musty, not exactly pleasant smell, and let me tell you, 10 liters of E.Coli definitely smelled up the whole lab. I felt bad for all my other lab mates who had to suffer through it with me.
After I made the culture, I had to centrifuge the liquid to isolate only the cells. These centrifuges are special heavy-duty ones that can spin at speeds over 50,000 times g-force. Let me put that in context for you: Most roller coasters can reach accelerations of about 4-6 times g-force. I would feel sorry for the cells but…..
Afterward, came the purification process. Since the protein I am purifying is considered a LCST–lower critical solution temperature–protein (that is, it dissolves at 4°C but aggregates at 37°C) we alternate hot and cold cycles to purify the protein.
First, we centrifuge at 4°C to get rid of the cell membrane and other parts of the cell that we don’t need. Then we incubate the liquid in the incubator above and then centrifuge again at 37°C to get rid of more unneeded parts in the cell. Repeat two more times and the protein is purified. Though it sounds like a pretty short process, it actually took me a whole week and a half to complete due to overnight steps, three hour long centrifuging processes, etc.
Finally, after the last centrifuging process, we then dialysize the proteins to get rid of any other salts that may be in the liquid which we re-suspended the protein in.
Here are all my bottles from the centrifuging process. I feel bad for hording all of them, but my mentor wants to keep them just in case something goes wrong since it is a two week long process.
After a hard day of work, what’ s better than spending time with friends? My favorite part about the SURF program is that it’s easy to get together with friends since we’re all staying on campus. And since most students at Caltech do decide to participate in the SURF program over the summer, there’s always plenty of people to spend time with.
Another nice thing about the SURF program is that there is plenty of good, cheap food around the Caltech area. Perfect for the poor, starving and lazy student :)
Till next time!!
