Thread: Thinking about Major in BioChemistry

I've lost my interest in Neuroscience, not completely. But I'm drawn away by the philosophical battles and debates going on in Neuroscience. I would much rather be in a purely scientific field. I also enjoy Chemistry much more than Biology, I do enjoy cellular anatomy and chemistry because its right down to the chemical processes of the cell.

Biochemistry, I was hoping to maybe work with Alzheimer's, and other Neurocognitive disorders, as I was initially trying to do with a Neuroscience pathway. I don't know a lot of people in Biochemistry as I did with Neuroscience. I was wandering if anyone here knows anyone in Biochemistry and what they are currently doing..

I've done different kinds of work in Biochemistry and I found it all exciting.

Probably the most helpful understanding is that it's mostly/all "chemistry"; the "bio" part is mostly/all working with biological processes (fermentation in bioreactors, PCR in thermocyclers, etc) and/or biological substances (monkey plasma, rat serum, antibodies, proteins, etc). Hopefully you won't have to "harvest" these things from the lab animals. Personally, I couldn't cut off a mouse's toe or tip of tail and I don't want to speak of harvesting internal organs.

Almost all biochemistry is regulated by the FDA, so expect a lot of documentation. Examples: The FDA's "Rule #1" is: If you didn't write it down, it didn't happen. Even though you've done the procedure a million times, you must have a copy of the latest revision of the procedure on the bench while you work. Your boss or coworker will review/check your work and the instruments, the solutions, the reagents, serial numbers, expiration dates, etc.

Expect to be brutally honest with your experiences (because you must record the truth anyway). I've heard talks given where: the lab techs fed the wrong batch of nutrients into the bioreactor, the agitator fell off in the middle of a run, or the lab tech applied the sparger steam instead of the sample port steam (thereby cooking the poor little microbes and putting a crimp in the growth curve).

Expect to work a lot with equipment (according to procedures, of course), anywhere from the lowly pH meters and fume hoods, to spectrophotometers, thermocyclers, bioreactors, HPLCs, and GC/MSs to sophisticated robotic analyzers such as Tecans, Hamiltons and Beckman Coulters.

Expect to be more than a procedure-follower and a button-pusher. Most bosses expect you to know the science happening in the machines, if only the general principles. Besides I found great enjoyment/interest in knowing the science being performed by the instruments. You'll get a gold star for the day if you can make quick/easy fixes to simple problems or give your company's repair technician or the instrument company's tech rep a "leg up" on troubleshooting the problem.

Expect sometimes/often to perform the required daily checks (aka "calibrations") on mundane instruments such as balances and pH meters because lazy lab users would rather crawl ten miles on their bellies over broken glass (just kidding) to find one they can use because some responsible person like you has already calibrated it for the day (or shift).

Expect to work in the lab in a minimum of gloves, a lab coat and safety glasses, and maybe a partial or full-blown bunnysuit. Biosafety Level 2 (BSL 2) labs are common, the scarier stuff is in the BSL 3 and 4 labs, although I don't readily see you working on Alzheimer's etc beyond BSL 2. However, if the cure involves injecting a gene into the patients' cells (!), then you might use viruses to do it.

Expect to dive into –20°C and –80°C freezers for samples, standards, controls, etc. Maybe even liquid nitrogen cryogenic dewars (–196°C).

That all sounds really great. Is your major biochemistry? What have you personally done, research? work? What has interested you most about what you do?

Actually, I'm an engineer.

For research, I did simple stuff such as measure the log removal of HCPs (Host Cell Proteins) from the cell culture harvest during the various stages of purification from batch runs of genetically modified CHOs (Chinese Hamster Ovary [cells]) in bioreactors. I know, that was a lot of information. There are two major types of cells in the mammalian body that continue to grow/multiply — one is the immune system, the other is the reproductive system.

If you need a mammalian cell to genetically modify to produce a mammalian protein, a common one used is CHOs. Don't ask me exactly why, but they're easiest to work with. You can use one cell for a billion years (jk!) to get the amount you need, or you can use a cell that continues to grow (ie, multiply), and that drastically cuts down the time required. So, the modified CHOs go into the bioreactor, which keeps them warm (at biological temp ~37°C), feeds them nutrients, oxygenates them, etc. They multiply until the bioreactor can no longer support them. During the run, you could drain off some of the "broth" and begin purifying it, or maybe the entire bioreactor is harvested at the end of the run. One is a continuous run and the other is a "batch" run.

But what happens is, the CHOs do what they naturally do while producing the protein that the inserted gene produces, and what they naturally do is produce their own proteins, called HCPs (Host Cell Proteins). Some of the cells are bound to die as well, so you also get some large cell parts (cell wall parts, nuclei, mitochondria, etc) floating around too. You'll obviously get some nutrients floating around too. Most of those can be filtered out using mechanical filters, but the soluble proteins and other molecules remain, especially the extra (usually) human protein you wanted it to produce.

So, let's say it's human insulin. Well, when your patients inject the drug into themselves, you only want insulin in it and not the CHO's HCP because they can cause a reaction and so they are called impurities (yuck!). So they must be filtered out, often by various means: columns, other filtration methods, etc. For each step, you want to take samples before the purification step and afterwards. Then you assay both for HCPs, see what reduction there is, if any (sometimes the methods don't reduce HCPs very much — very disappointing ). Anyway, you need a way of measuring the concentration of HCPs.

Enter the mice. You take the non-modified CHOs and grow them. Then you take the harvest, filter out the dead cells parts, and inject the HCP-rich solution into mice who then produce antibodies for those CHO HCPs. Then you harvest the blood (? I guess) from the mice — poor mice, put them in a device that holds them (called a"crush"??), then snip a toe or tail and let them bleed out. Poor mice! You go through another process to purify the antibodies, which you use to coat your microplates. Now, I just talked about "you" producing mouse antibodies for CHO HCP (what we would call mus α-CHO HCP), but I don't really mean YOU, hopefully this has been done for you. But you would use them to coat your microplate cells with them, so when you put your samples in, the antibodies will grab ahold of them. Then you perform an ELISA like that with samples, standards and controls.

So if the "before" sample concentration measures, say, 2.3 units, and the "after" sample concentration measures, say, 0.023 units, then the removal is 2 logs. 2.3/0.023 = 100 = 10², and the exponent is your "log" removal. Get it? A 2 log removal is pretty decent, you'd love it if it were higher, maybe 3 or more. Something less that 1, say 0.5 or maybe 0.3 or 0.2 would probably be disappointing, although it all depends on what you were expecting.

And so, by testing, I was helping researchers develop the purification method to use on the harvest to obtain a very pure solution of only the protein of interest. If a purification step had a huge log removal, they'd keep it, if it was [too] small, they would substitute a different method.

Now, if you work at a small company, you might be involved with most of this work — culturing in the bioreactor, performing the various purification processes, and testing for log removal. Hopefully your company would farm out the mouse antibody production to a specialized contractor. Same with getting the human insulin gene into the CHO cells to begin with. If you work at a large company, you would probably work on just one specific part of the whole process: culturing, purifying, testing, etc. In fact, the culturing might run anywhere from a few days to a couple weeks, depending on the size of your bioreactor, but it's 24/7, so you must have at least two or three shifts so that means coordinating work among various teams.

I did other work I can describe later. But it was all very exciting.