Lysine- Essential Amino Acid

            Lysin, L-Lysine, amino acid K,  is an essential amino acid, which means the body can not produce it, in humans. It must be taken in through diet or by supplementation.  Lysine was first isolated from casein (a milk phosphoprotein) by Drechsel in 1889.(Walter Kluwer) Lysine is important for proper growth, and plays an essential role in the porduction of caritine, an nutrient responsible for converting fatty acids into energy and helping to lower cholesterol. Another role of lysine involves the absorption of calcium in the body as well as a role in the formation of collagen, and substance important for bones and connective tissues. A common use of lysin is to decrease to proliferation of the herpes virus.

            Foods that are rich in protein are a good source of lysine which include red meat, pork, poultry, cheese, nuts, eggs, and soybeans to  name a few. Low lysine levels symptoms include fatigue, nausea, dizziness, loss of appetite, and anemia. Since  it helps the body absorb calcium and decreases the amount of calcium that is lost in urine, some researchers think lysine may help prevent bone loss associated with osteoporosis. Lab studies suggest that lysine in combination with L-arginine makes osteoblasts more active and enhances production of collagen. (University of Maryland).

         The molecular formula for lysine is C6H14N2O2 with a molecular weight of 146. 19g/mol. It's Isoelectric point(pH) is 9.59 (Kirste) The pH values of each group are as follows: the alpha carboxylic acid group=2.18pH, alpha amino group=8.95pH, and finally the R side chain (CH2)4NH2=10.53pH.(Parrill)

The functional groups on it's side chain include an amino group (NH2) as well as an alkane carbon chain. 

         Lysine's long flexible side-chain with a positively charged end makes it suitable for binding to molecules with many negative charges on their surfaces. "For example, DNA-binding proteins have their active regions with arginine and lysine. The strong charge makes these two amino acids prone to be located on the outer hydrophilic surfaces of the proteins." The alpha amino group often participates in hydrogen bonding as a general base in catalysis. (New World Encyclopedia)

One of the peptides that contains Lysine is the mycobacterial dideoxymycobactin T cell antigens
 which was synthesized to fight TB.

                                                            (Antigenic DDM) 5

Sources:

1.Lysine. Review of Natural Products. factsandcomparisons4.0 [online]. 2005. Available from Wolters Kluwer Health, Inc. Accessed April 23, 2007.

2. Lysine. University of Maryland Medical Center. http://www.umm.edu/altmed/articles/lysine-000312.htm

Accessed March 23, 2011

3. Parrill, Abby. Amino Acid Structures. Michigan state University. http://www.cem.msu.edu/~cem252/sp97/ch24/ch24aa.html

Accessed March 23, 2011

4. http://www.newworldencyclopedia.org/entry/Lysine

5.Young, Moraski, Miller, and Moody. Solid-phase synthesis of mycobacterial dideoxymycobactin T cell antigens

EAS in the Research Community

"Bromination from the Macroscopic Level to the Tracer Radiochemical Level: ⁷⁶Br Radiolabeling of Aromatic Compounds via Electrophilic Substitution"


         -The aim of the research accomplished in this article was to explore the differences between the oxidative bromination reaction under small-scale macroscopic vs tracer level radiochemical condition, explored in terms of effective brominating agents. The development of experimental protocols for successful radiobromination at the tracer NCA-scale should be applicable to the synthesis of other radiobromine-labed organic compounds such as PET radiopharmaceuticals and radiotherapy agents. Bromine-labeled compounds have advantages over iodine-labeled compounds; the stronger C-Br bond results in less dehalogenation, and unlike iodide, bromide does not accumulate in the thyroid. 


They found that ipso substitution by electrophilic dematallation effectively "introduces radiobromine regiospecifically into organic compounds containing aromatic rings, but competition can occur with other reactive sites, such as open positions on an activated aromatic ring and amine or amide groups."


 In one particular reaction hydrogen peroxide/acetic acid(2:1) was used in the radiobromination of a 5-tributytin substitutud furfural, in in which the electron-rich furan ring is deactivated slightly by the aldehyde group to make the compound in Image 1. It was used in the synthesis of 76Br-labeled progestin 16alpha, 17alpha-dioxolane for breat tumor imaging and radiotherapy. 


                                                                           (Image 1)

Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2743097/?tool=pubmed