I have a student who has been working on a "research" project for me. The project is to extract a protein called concanavalin A from Jack beans. I use quotes because this isn't a novel area of research by a long shot. My goals for this project were to #1 develop a method of extraction that I could use in my Principles of Biochemistry course and #2 teach my student a variety of laboratory methods.
Concanavalin A (con A) is a lectin from the Jack Bean. A lectin is a protein that binds carbohydrates. In the case of con A, it binds with glucose and mannose but not galactose (or other carbohydrates). It does not have enzymatic activity, and its role in the plant is not clear (as is the case for most lectins).
My student has been working on this project all semester. Briefly, the Jack beans are soaked in pH 4-5 buffer and then blended in a blender. The supernate is removed after centrifugation. It is saturated with ammonium sulfate. The precipitate is collected and dialyzed against 1M NaCl. The protein solution is passed through a sephadex column and the Con A binds with the sephadex. It is displaced by glucose. The solvent used in the sephadex column is 1M NaCl (that's important to remember for this story).
Through trial and error and up the steep learning curve that is undergraduate research, my student eventually got enough sample to the sephadex column part. She loaded the sample onto the column . However, instead of running 1 M NaCl through the column, she used 1 M HCl instead. ugh! There is a big difference between a pH of 7 and a pH of 0. It wasn't good for the protein which, for the most part, appeared to cease to exist intact.
I should point out that she is NOT a bad student or a lab disaster waiting to happen. She is a very good student and one who absolutely knows the difference between NaCl and HCl. But these things happen. Unfortunately for her, that meant the end of her project.
We've all been there. If you've spent anytime in a lab, you've probably made a stupid mistake. I'm not talking about the frustration of dealing with things that don't work. I'm talking about the things that you ruined by a stupid mistake. It happens. The goal is to never repeat it.