BIOC 223

One awesome post linking music to biochemistry last week reminded me to share with you all an upcoming event in the Science Center, aptly named “Music at the Science Center”! On Tuesday, March 11th, from 4:30-5:30, I will be playing a set of songs, mostly original and perhaps some not-so-original songs on piano and guitar.  I don’t have any finished songs about biomolecules at the moment (still in the works!), unfortunately, but I do have one about couscous….isn’t that considered a carbohydrate??

I’m very excited for the show, and for the upcoming events (I’m just the first leg of the series!) because any chance to showcase the diversity of interests within science majors is always great. We definitely put in hours in the lab, because we’re curious and driven by logic and analysis, but it’s always nice to see what else drives us.  I guess this also prompts me to ask the class – what other activities are you involved in?

The remainder of my post today will be about collagen, and how today’s class helped solidify my brief experiences with this cool protein while working in a cartilage lab this past summer. One of my first independent experiments was immunohistochemically staining for Collagen Type II (yes! there are multiple types and subtypes of collagen, which only adds to the confusion), so I have a certain fondness for it. I remember looking at the staining of the microscope, not sure what to expect.

Because collagen is so structurally sound, it makes sense that it comprises a decent percentage of the extracellular matrix of cartilage tissue. You can actually see this structure in action – the brown stains from the IHC experiment showed a very spongy, interconnected web of collagen – what you might imagine the structure of bone marrow might look like.

I recall my mentor mentioning hydroxyproline assays, affectionately termed “hy-pro” tests. I also recall  The triple helix motif was also mentioned extensively, though at that time I didn’t have a good idea of what that motif would look like on a primary sequence level or why the three helices would be motivated to bind in such a fashion (now I know – often it’s due to the hydrophobic faces on the three helices!)

My reminiscence about my time in the cartilage lab has really helped me appreciate everything that I observed in my time in this cartilage lab, but never really got a chance to understand how these observations fit into a bigger context.  In class, there have been lots of words that trigger memories and create “a-ha” moments for me,  which help put my past lab experiences into a more academic context. This is strange for me, becaus usually I  like knowing the theory extensively before putting it into practice. I am finding that the reverse – learning the practical uses and properties of collagen before understanding the theoretical structure of collagen, is also to my surprise a wholly satisfying experience as well!

The primary structure is mostly made of glycine and alanine. Silks are often called block copolymers because it consists of blocks of glycine and alanine. Alanines are mainly found in beta sheets of the nanofibril while glycine is mostly found in helical and beta turn structures. Silk is unlike any material due to the combined qualities of hard crystalline segments and elastic amorphous regions.

Also, silk filament derived from silkworm Bombyx mori is composed mainly of sericin and fibroin proteins. A really cool technique currently being developed is called electrospinning whereby  an electrical charge is used to form very thin fibers from a liquid.

SEM images of pure silk

http://www.intechopen.com/books/advances-in-nanofibers/fabrication-of-nanofibrous-scaffolds-by-electrospinning

If only we could produce such efficient, flexible, strong materials as well as nature! The symmetry and functionality is really incredible!

So today in class Prof. Didem brought in halva, a delicious dessert that contained walnuts. Fortunately, I do not have to constantly check labels to make sure they are “nut free” but when I babysit I have to constantly look for these labels. So today I decided to actually find out what happens during a allergic reaction to peanuts.

While on Google, I was surprised to find that histamines are the prime players in allergic responses. Histamines are heavily involved in local immune responses and are derived from  the decarboxylation of histidine. Let’s pretend I’m allergic to peanuts and I accidentally ingested a peanut butter cookie. . .

At first, the body mistake the peanut for a deadly substance and release antibodies, which in turn release histamine to eliminate the problem. Histamines then run to different parts of the body producing different biological response. For example, the heart contains histamine receptors that drastically decrease heart rate. Skin also contains these receptors and when they detect histamine they cause swelling. Breathing issues also arise when receptors on the lungs detect histamines.

I didn’t really look into the medical solution for peanut allergy reactions but given the important role of histamine in causing these biological responses, I would assume that there would be chemicals that block the binding of histamine to its receptors. I think this is really cool because it delved into the field of immunology and gives me a better idea of how scientists approach these problems.

Going off of Houda’s awesome post, I looked into browning. Not being very handy around a kitchen myself, I had always though of “browning” as the undesirable decomposition of foods, especially fruits and vegetables. It turns out that the desirable browning as a result of the Maillard reaction, which account for many delicious carbohydrates and meats, and the brown color that cut fruits eventually reach, are categorized as nonenzymatic and enzymatic browning, respectively.

In enzymatic browning, there are obviously enzymes that are involved, which oxidize phenols to melanins and quinones, producing a brown color. I’m sure everyone knows to store their fruits in the refrigerator to slow down browning; or even sprinkle some lemon juice on their apples for extra zest, especially if there’s no refrigeration available. The most interesting aspect is the chemistry behind this part! Low temperatures slow down browning since they decrease the rate of reaction, which explains why they wont turn brown for a few hours, but probably not much longer than that. Acids lower the pH and remove the copper cofactor, preventing the enzymes that are involved in browning from functioning!

It’s so enlightening to find out that a small life hack I learned in elementary school is based on food chemistry and preventing an oxidation reaction.

Based on the title, you can probably tell that I really love Pringles. You may as well! But, after our short introduction to carbohydrates in class today and talk about Pringles, you may have changed your mind about it since.

Pringles are made from Olestra, which is a sucrose polymer that is a fat-based substance. While natural fats have three fatty acids attached to glycerol, olestra has six to eight fatty acids attached to a sucrose molecule. Since it won’t fit the enzymes in the body that break down fats, sucrose polyester passes through the body undigested. Therefore, it is a nonnutritive fat, meaning it produces no calories. Because it can’t be digested, consuming large quantities of these products causes intestinal discomfort These fats are found in Ruffles as well.

Next time you pick up a can of Pringles or bag of Ruffles, you might want to reconsider your choices! At least, don’t eat them all at once! 🙂

With inspiration from the delicious sweets from today’s class, I decided to look into another carbohydrate reaction that makes for sweet desserts: caramelization.

Caramelization apparently is the result of the decomposition of more complex carbohydrates (ex. sucrose) into simpler sugars (ex. glucose and fructose), followed by a condensation reactions between these simple sugars! This occurs at higher temperatures, and the water produced from the reaction boils out. The new compounds produced, like diacetyl, make for the flavor of caramel.

Although the Maillard reaction, which was mentioned in class, also results in “browning,” it is different from caramelization in that it involves reactions between a sugar and an amino acid, rather than between sugars – specifically, an oxidation reaction between the amino acid’s amino group and the sugar’s carbonyl group.

In the chemical engineering lab that I just started working in this semester, we are working to find biosynthetic hydrogels/polymers for the human body. There are several gel ideas that are currently being tested in the lab and they are all SUPER cool. One of the ones that I heard of is a gel that is liquid at very low temperatures (so that it can be sucked up into a syringe easily) and then when it gets injected into the body, it becomes solid-like and stretchy and they are hoping it may help people with blood clotting disorders. Isn’t that the coolest thing ever?? Anyway, the one that I am working on with my post doc is a gel that can successfully act as a selectively permeable membrane to certain proteins. (You will hear more about this in blog posts to come, I can promise that!) Basically, I’m working with my post doc to first purify many many proteins Its interesting, my post doc explained to me recently that in bio/chem/biochem labs the point of the experiments are to purify the protein to its highest level of purity, while in chem/biochem engineering labs (or in engineering in general) the point is to purify the proteins, but a more important point is to have as much volume of protein as possible in order to test it later. But something super interesting that I thought I’d share was how we are working on purifying the part of the protein that we want. Essentially, the structure of the protein

We’ve discussed the chemistry behind and hair curl and perms a few times, but I started wondering about some of the less-permanent hair styling options out there. A hair “perm” is so-called because it is permanent: a strong reducing agent reduces the disulfide bonds in the hair, which is then physically straightened and re-oxidated to form new disulfide bonds in a different configuration. In this case, covalent bonds are permanently disrupted. But, what about non-permanent hair styles? Specifically, I was thinking about that middle-school locker room staple, the hair straightener. How does heat affect the bonds in hair?

A quick Google search later, I have my answer. Electronic straighteners work using the same general procedure as perms:  bonds within the hair are broken, the hair is physically straightened, and the broken bonds are reformed in the new, straight configuration. The difference lies in which bonds are being affected. Whereas the chemicals used in perms changed covalent bonds, heat styling disrupts noncovalent interactions -hydrogen bonds. Electric straighteners apply heat to break hydrogen bonds in the alpha keratin protein in hair. The hair shaft is ironed flat and held that way by the straightener’s plates for the H-bonds to reform in a”flat” shape, leading to straight hair. However, the nature of hydrogen bonds also causes the effect to be temporary. Hydrogen bonds in your hair interact with water in the air. More moisture cause the hair to reform its original shape as the original hydrogen bonds are restored. This is why heat-styling is easily undone by humidity.

In any case, although the effects of heat-styling might be temporary, prolonged use can be damaging to the hair. Being addicted to the hair straightener can lead to frizz, dryness, and split ends. If only my middle-school self knew about the science behind post-gym locker room primping.

Sources:

http://www.ccmr.cornell.edu/education/ask/index.html?quid=708

http://www.livestrong.com/article/190915-hair-loss-caused-by-heat-straightening/

http://www.ncbi.nlm.nih.gov/pubmed/15037918

On my way to the airport from home, my brother, father and I had actually been talking about 3D printing. While my father was getting gas for the car, my brother and I realized we didn’t really know how it worked, so I clearly remember looking it up in the car as we waited.

That made using the models pretty cool.

Anyway, apparently Chuck Hull, the inventor of 3D printing is being inducted into the National Inventors Hall of Fame! 3D printing technology was actually invented in the 1984, when  “Hull had a realization: if you pointed a highly focused UV light at a special, goopy material (called a “photopolymer” ), the material would instantly turn solid wherever the light would touch. If you did this repeatedly, layer by layer, you could “print” an object into existence. He dubbed it “stereolithography“, and bam! 3D printing was born.” (Hahaha, I really enjoyed the article’s description, which is why I inserted it.)

He joins other famous inventors such as Thomas Edison and the Wright Brothers, and even Einstein.

…pretty cool! Apparently his original patents are also expiring soon, which means the original technology could be available for public use soon.

Source: http://techcrunch.com/2014/03/04/the-father-of-3d-printing-is-being-inducted-into-the-national-inventors-hall-of-fame/