Maria O. Longas
Department of Chemistry and Physics
Welcome to my chemistry page, my fun page.
Do you know what the chemical structure shown below represents?
Take some chemistry courses, and you will find out. Regardless of what you are majoring in, a science course will expand your intellectual horizon. I went to college to major in literature, took a chemistry course and was mesmerized by it.
Please check the links listed below. Most of them contain what some of the students in my organic chemistry courses had to say about chemistry, and what learning this subject meant to them.
The Millard E. Gyte Builting, where the Chemistry Department is located.
Black-eyed Susan, in Founder’s Plaza
Photo by Maria O. Longas
Research Interests and Projects
- Elucidation of age-mediated chemical changes of glycosaminoglycans (GAG) and proteoglycans in human skin has been a concern in my laboratory for several years. The purpose is to determine the chemical alterations, the age-related disorders in which they play pathogenic roles, and to develop appropriate therapeutic methods. The enzymes responsible for some of the age-mediated alterations of skin GAG are also being investigated. We have found that hyaluronic acid (HA) (a glycosaminoglycan) loses its N-acetyl moieties in the 7th decade of life, due to the action of an age-induced enzyme that we call HA-N-Deacetylase and is presently being sequenced.
- We are also working on identifying specific sulfate positions on heparin (HP) and dermatan sulfate (DS) chains, using chemical or enzymatic desulfation followed by spectroscopy. N-bonded sulfonate groups of heparin have been identified, using various spectroscopy methods, like Fourier Transform Infrared Red and Raman spectrometry, in addition to nuclear magnetic resonance (NMR) spectrometry. This work is important, because of the many medical functions of HP and DS that require sulfonation at specific positions on the GAG chains.
- Oligoxylans are polydisperse heteropolysaccharides prepared by sulfation of beechwood xylans (SP54TM). These heteropolysaccharides have anti-HIV activity. In collaboration with Dr. Audrey Stone of the National Institutes of Health, who prepares and provides the oligoxylans, we are investigating the specific oligoxylan conformation or conformations that have anti-HIV activity. Using NMR spectroscopy, we have identified both axial and equatorial sulfates in these heteropolysaccharides.
- Apoptosis is caused, among others, by incomplete or no protein folding. Using various spectroscopy methods, we are studying with Dr. Dipak Banergee of Puerto Rico Medical School, the effect of oligosaccharides on glycoprotein folding in endothelial cell culture in vitro.
- Heparin, a GAG with potent anticoagulant activity, is known to inhibit the proliferation of endothelial cells in vitro. This property has anti-plaque development effects in atherosclerosis. Therefore, in collaboration with Dr. Hari Garg, of Harvard Medical School, we are investigating the effect chemical, N-desulfonation of heparin on its antiproliferative activity.
- The oversulfation of DS, the preponderant GAG of human skin, appears to be responsible for the overproduction of collagen during skin development. Therefore, the effect of DS oversulfation on kelloid formation is presently under investigation.
- In collaboration with Drs. Dean Harley and David Bennett of Rush Alzheimer’s Disease Research Center, we are working on the effect of GAG sulfation on the development of ?-Amyloid fibrils in Alzheimer’s disease. This work is supported by the Alzheimer’s Disease Research Foundation, since January 1, 2010 till December 31, 2012. The PI is Maria Longas.
Marie Kellemen and Elizabeth Morrison received an Undergraduate Research Grant for $ 829.50 to work on the project entitled: “ Elucidating the Role of Heparin O-Sulfonation and N-Sulfonation on Biologic Activity and Disease.
Francis Enane and Jamie Luther got an Undergraduate Research Grant for $ 965.61 to work on the project entitled: “ Purification of Hyaluronic Acid N-Deacetylase.
Francis Enane received an LSAMP award.
Francis Enane received a McNair Grant to work on “Peak Fit. A Unique Method to Identify Various Sulfonate Groups on Heparin.
Ashok Kotapati, graduate student in Biological Sciences received $ 500.00 from the Glycoconjugate Society to attend the 20thInternational Symposium on Glycoconjugates to be held in San Juan Puerto from November 29th through December 4th, 1009.