National Science Foundation Pre-doctoral Fellowship
Biotin is an essential vitamin for humans; it must be included in infant formulas and in fluids for intravenous nutrition. Even though it is a necessary component of our diet, we do not yet know the mechanism by which biotin, also known as vitamin H, is synthesized in the body from dethiobiotin. The enzyme that accomplishes this conversion has been termed biotin synthase. This enzyme catalyzes the insertion of sulfur at nonactivated positions of dethiobiotin, between carbons C1 and C4, to generate biotin. This mechanism is of interest because it appears to involve uncommon chemistry and because of the commercial value of the product. Biotin is sold as a pharmaceutical and as a food and cosmetic additive. This water soluble vitamin is essential for the growth and well-being of animals and humans, and it is used in the formation of fats the utilization of carbon dioxide.
Prof. Richard H. Holm's bioinorganic chemistry class sparked my interest in the understanding of enzyme mechanisms as model systems for the design of more selective drugs and better synthetic catalysts that allow us to run reactions with good yield, little waste, and inexpensively. Having worked for two years with Prof. JoAnne Stubbe on the mechanism of nucleotide reduction in E. coli by ribonucleoside diphosphate reductase, I have come to appreciate the positive effects of an understanding of this mechanism in the synthesis of more efficient drugs for the treatment of cancer and viral diseases. Increased knowledge of the biotin biosynthase mechanism should allow us to produce biotin more efficiently, and the knowledge gained from this mechanism could be applied to similar enzymes.
Despite recent advan...
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...should aid me in designing more successful experiments.
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Madison speaks of the problems of the present attempts at a new government saying “our governments are too unstable, that the public good is disregarded in the conflicts of rival parties, and that measures are too often decided, not according to the rules of justice, and the rights of the minor party, but by the superior force of an interested and over-bearing majority”.
Madison begins perhaps the most famous of the Federalist papers by stating that one of the strongest arguments in favor of the Constitution is the fact that it establishes a government capable of controlling the violence and damage caused by factions. Madison defines that factions are groups of people who gather together to protect and promote their special economic interests and political opinions. Although these factions are at odds with each other, they frequently work against the public interests, and infringe upon the rights of others.
David and John Free. (26 Nov 2006). MadSci Network: Chemistry. Retrieved on March 6, 2011, from http://www.madsci.org/posts/archives/2007-02/1171045656.Ch.r.html
Madison argues the big problem in democratic politics is factions. A faction is a group of people with common beliefs that they potentially pursue against the good/common interest. Factions are inevitable because there will always be haves and have not’s. Factions set up uncertainty into Democratic Systems. To control the effects of factions Madison states he believes a Republican style government would be more effective than a pure democracy.
Madison defines factions as a group of people who gather to protect and promote their special economic interests and political opinions. According to Madison, factions can either be a majority or minority. These factions work against each other, ultimately leading to the work against public interest. Basically, factions are political parties, because people are acting on common passions or interests.
Schweitzer, M.H., Watt, J.A., Avci, R., Knapp, L., Chiappe, L., Norell, M. et al. 1999. J. Exp. Zool. 285: 146-157.
To Madison factions, or groups of citizens with mal-intent for the new government, are a threat to the new government and it is impossible to find an acceptable remedy. Madison considers both liberty and the idea of having opposing opinions to be the key sources to factions. This also proves to be the reason why factions can never be eradicated completely.
...Hallert, C., C. Grant, S. Grehn, C. Grannot, S. Hultent, G. Midhagens M. Strom, H. Svensson,
The three types of muscle cells are cardiac, skeletal, and smooth. Cardiac muscles are only found in and near the heart. They push blood through the heart, and are involuntary (not controlled by the nervous system). Skeletal muscles are attached to the tendons and bones. They stabilize joints, help with posture, and power voluntary movement. Smooth muscles are found in organs. They work together to move substance like food through the body, and are involuntary. Muscles use proteins called actin and myosin to move. Calcium ions bond actin and pull it apart, which opens a place for myosin will bond. Actin and myosin push and pull against each other, which causes the expanding and contracting.
The sarcomere is found in structures called myofibrils which make up skeletal muscle fibres. Within the sarcomere there are various different proteins. One of the most significant, myosin is found in the thick filaments of the sarcomere. Although both cells contain myosin, it is important to highlight that smooth muscle cells contain a much lower percentage of myosin compared to skeletal muscle cells. Despite this, myosin filaments in smooth muscle cells bind to actin filaments in a manner similar to that in skeletal muscle cells; although there are some differences. For instance, myosin filaments in smooth muscle cells are saturated with myosin heads so that myosin can glide over bound actin filaments over longer distances, enabling smooth muscle cells to stretch further, whilst in skeleta...
To the normal Chinese man during the early 19th century, opium was nothing more than a luxury that only those of higher power or influence could indulge themselves in. Yet by the middle of the 19th century opium had become a commodity that everyone could have and that at the same time they seemed to need. Even though it was now such a big part of the normal chinese culture, it did not benefit the people nor Chinese culture, it did not benefit the people or the government. The only benefit it did seem to have was towards the British. The British were flourishing from the new Chinese market for opium, where the Chinese were beginning to turn into addicts of a drug that was slowly poisoning their way of life. The people no longer were concerned about their advancement and safety of their family but about how and when they would be able to get more opium. The Chinese government was not pleased about this and decided to take a stand that would, in the long run, only damage the very people they were trying to protect. This stand came to be known as the First Opium War (1839-1842). By the end of the First Opium War China had begun to lose its sense of identity through the use of treaties and encroachment of foreign countries, starting with the British and their Treaty of Nanking.
Cardiac muscle is a type of involuntary muscle found only in the walls of the heart, specifically the myocardium. Cardiac muscles contract automatically to tighten the walls of the heart in a rhythmic fashion (pp.212-216). The heart beats nonstop about 100,000 times each day (p.18). Smooth muscle is a type of involuntary muscle found within the walls of blood vessels such as in small arteries and veins. Smooth muscle is also found in the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, and the respiratory tract. Skeletal muscles are voluntarily controlled and are attached to bones by tendons. Skeletal muscles also vary considerably in size and shape. They range from extremely tiny strands such as in the muscle of the middle ear as large like in the muscles of the thigh (Martini, 2000). The three individual muscle types also serve five main functions. The five basic functions are movement, organ protection, pumping blood, aiding digestion, and ensuring blood flow.
Riggio, Ronald E., Ph.D. "Will Swearing Harm Your Child?" Psychology Today. Sussex Publishers, LLC, 18 May 2012. Web. 13 Feb. 2014. .
Honesty is one of the most important traits that any relationships relies on. A good friend
One of the most important uses of organic compounds is in medicine. All living things have four organic molecules - carbohydrates, proteins, lipids and nucleic acids. Without carbon chains and nucleic acids, DNA would not exist. Enzymes which produce chemica...