BIOC 223

Food and drinks often use artificial sweeteners as another option to decrease our calorie intake and a way to lessen our cravings for something sweet. These low-carloier sweeteners are often used to sweeten food and drinks for less calories and carbohydrate when they replace sugar. Only a small amount is need when sugar substitutes are used. Most of these substitutes cannot be digested so they provide no extra calories. Five artificial sweeteners that have been tested and approved by FDA include acesulfame potassium, aspartame, saccharin, sucralose, and neotame.

Since we spent a lot of class time talking about the structures of carbohydrates and glycosidic bonds that are formed, I looked into the structure of sucralose, which is often known as Splenda. Looking at the structure of sucralose below, we see some similarities like the many hydroxyl groups and the five and six membered rings with oxygen. The difference is the the three chlorine atoms that might affect how enzymes interact with this substitute to prevent the degradation of this molecule in the body.

Since we talked about lactose intolerance in class this week, and I’m lactose intolerant, I decided to look a little more into it. Most people know that this problem is caused by a lack of lactase, which breaks down lactose into glucose and galactose. What’s interesting is that most animals become lactose intolerant after infancy and weaning, so no one is born lactose intolerant. The continued production of lactase in humans is actually known as lactase persistence and a relatively recent evolutionary development (http://www.ncbi.nlm.nih.gov/pubmed/14616060).

Even more surprising is that most of the human population is lactase non-persistent. So one way of looking at it is being lactose intolerant is actually the norm! This persistence is caused by several mutations (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3048992/). It is interesting to see how the development of society has selected for certain mutations and actually changed the physiology of certain populations that are more reliant on dairy in their diets. Lucky for those who are lactose intolerant, there are so many dairy substitutes that taste almost like the real thing, such as Lactaid, which provides pre-made lactase!

Hey everyone! I don’t know about all of you, but I know that I personally am starting to try to narrow down what kind of programs I want to apply to after Wellesley–do I want to stick with biochemistry, or do I want to lean a little more toward biology, or maybe toward chemistry? Well, a speaker in my microbiology course this week gave a talk about microbial interactions, and she happened to mention a chemist that I decided I really wanted to look into, and I thought maybe people in this class would like to read up on him too! His name is Michael Fishbacher from UCSF, and from his website, http://www.fischbachgroup.org/research, he describes his research goals as follows:

1. Natural products are produced by the human microbiota.

Most known natural products come from exotic soil and marine bacteria. We have recently found that bacteria from a surprisingly underexplored niche — the human body — are prolific producers of natural products. We are currently mining gut- and skin-associated bacteria for natural products that play important roles in human physiology and disease.

2. Natural products mediate microbe-host and microbe-microbe interactions.

We are particularly interested in the mechanisms by which natural products from the human microbiome mediate interspecies interactions. We are focusing on interactions between gut bacteria and humans that are relevant to human diseases like Crohn’s disease and obesity, and on interactions between different species of skin bacteria that likely play a role in susceptibility to infection by bacterial pathogens like Staphylococcus aureus.

3. Connecting natural products to the genes that encode them accelerates discovery.

We are developing a bioinformatic algorithm that automatically identifies clusters of small-molecule-producing genes in bacterial genomes. An early version of this algorithm has already identified thousands of new gene clusters in the thousands of bacterial genomes sequenced to date, many of them in species from the human microbiome. We are refining this algorithm so it can predict the chemical structure of the small molecule encoded by each gene cluster. In the near future, we believe this tool will provide us the first global view of the small molecules produced by bacteria, which will serve as a powerful predictive tool for our experimental efforts.

I don’t know about the rest of you, but I find this research really interesting!

I’ve been pretty fascinated by the variety of carbohydrates and their derivatives that we’ve been learning about. Amazing how mere C,H,O (N,S) can form the world of sugars that we know of.

My interest has been peaked particularly by the reduced sugars- the sugar alcohols or itols. Both sorbitol and xylitol are common ingredients in chewing gum. It turns out that these sugar alcohols taste sweet like sucrose but cannot be fermented so the bacteria in the mouth cannot use them to produce tooth corroding acid.

One can happily enjoy gum without worrying about tooth decay but not too much because, the accumulation of undigested OH rich sugar alcohols has laxative effects as a result of all the water the OH groups attract in the intestines.

An amazing instance of where 3D Printing does some amazing things…

Stephen Power was in an accident two years ago, during which he severely injured his face. So recently at the Morriston Hospital in Wales, they reconstructed his face. They were able to do this accurately because they had been using 3D model of his skull – printed.

The doctors say that hopefully they can make the technology more efficient and cheaper in the future. Being able to print a person’s 3D face eliminates a lot of the guess work as to where things go. I didn’t know for instance that “Without this advanced technology, it’s freehand. You have to guess where everything goes. The technology allows us to be far more precise and get a better result for the patient.”

So with 3D printing developments there are also a lot of biomedical implications! If doctors can get actual models ahead of time, it shortens the planning time considerably.

Below is the article for anyone wanting to read more:

http://www.huffingtonpost.com/2014/03/12/3d-printing-face-rebuilt_n_4951250.html?utm_hp_ref=mostpopular

As with many of my classmates, the relationship between food and biochemistry is incredibly interesting to me! So, in this post, I wanted to talk about one of my favorite foods – mochi. If you’ve ever tried mochi, you know that it is very stretchy rice cake, usually stuffed with red bean paste.

In class, we discussed how some polysaccharides can be completely linear, while others branch at various places by connecting to different carbon numbers on the carbon ring. What actually gives mochi its characteristic elasticity is this small difference – the starches that make up mochi have many branches, making it more “solid” and stretchy and delicious!

Saw this post and thought it was the coolest thing ever. Everybody I know loves Sriracha sauce, and now the ACS explains why! I thought this was particularly interesting since we have been discussing how taste works.

http://www.npr.org/blogs/thesalt/2014/02/24/281978831/sriracha-chemistry-how-hot-sauces-perk-up-your-food-and-your-mood

In simplified language, Sriracha contains jalapenos, which are filled with two compounds – capsaicin and dihydrocapsaicin. These compounds bind to the surface of our taste receptors, called TRPV1, which are also activated by high temperatures. When capsaicin and dihydrocapsaicin bind to the receptor surface, they trigger a pain response similar to the one we experience when we touch something hot. To help adjust to the pain, your nervous system also starts a series to soothe the pain. It does this by releasing endorphins, which are morphine-like compounds that produce a natural high and makes our nerves less sensitive.

I just had a small “A-ha!” moment. 🙂 I was reading about lysozyme, and how it breaks carbohydrate chains. In my PyMOL image I had included the “sugar” to which lysozyme binds. Now I finally know what it is!

I have to say, I knew after being introduced to MALDI-TOF in biochemistry a few weeks ago that it was an amazing piece of equipment, but I feel like I just keeping learning more and more amazing things about them!! In Environmental Microbiology (which, by the way, I recommend to everyone!), we just read a paper titled “Microbial metabolic exchange in 3D” by Watrous et al. that used MALDI-TOF imaging mass spectroscopy, which is apparently used for tissue samples, in a really brilliant way. They measured production of chemicals by microbes in agar plates by sectioning the agar and analyzing the inner area, rather than simply whatever grows on the surface. Better yet, they could use this technique to see how metabolic chemicals released by one microbe, such as Bacillus subtilis, influences the production of chemicals and metabolites by other microbes, for instance Streptomyces coelicolor. They were even able to measure the output by individual hyphae of Candida albicans in the presence of Pseudonmonas aeroginosa, which requires high levels of precision, as I’m sure you can imagine. I just thought it was really interesting to see all the uses of something that I first saw in biochem lab!