Dr. Neeraj Gupta of the UK Chemistry Department will be presenting a seminar entitled Developing Green Technology for the Synthesis of Value Added Chemicals and Biologically Active Compounds.

Refreshments will be served at 3:30pm.

All students welcome!

Faculty Supervisor: Dr. Folami Ladipo

This is an opportunity for the department's graduate students, as well as all other interested persons, to discover the research taking place in the Chemistry Department at the University of Kentucky. First-year graduate students are strongly encouraged to attend with their blue sheets, to get signatures from potential research mentors.

Dr. Trevor Creamer of the University of Kentucky's Molecular and Cellular Biochemistry Department will be presenting a seminar entitled, The Disordered Regulation of Calcineurin.

Abstract: Calcineurin (CaN) is a highly regulated Ser/Thr protein phosphatase that plays critical roles in learning and memory, cardiac development and function, and immune system activation. Alterations in CaN regulation contribute to multiple disease states such as Down syndrome, cardiac hypertrophy, Alzheimer’s disease, and autoimmune disease. Despite its importance, CaN regulation is not well understood at the molecular level. Full CaN activation requires binding of calcium-loaded calmodulin (CaM), however little is known about how CaM binding leads to CaN activation. I will present evidence that the 95 residue CaN regulatory domain, where the CaM binding region is located, is disordered. The binding of CaM to CaN results in the regulatory domain folding. Folding of this regulatory domain in turn causes an autoinhibitory domain to be ejected from CaN’s active site. It is this binding-induced disorder-to-order transition that is responsible for the activation of CaN by CaM.

Facutly Host: Dr. Jason DeRouchey

Dr. Barbara Finlayson-Pitts of the University of California, Irvine will be presenting a lecture as part of the UK Chemistry Department's Lyle Dawson Lecture Series.  It is entitled Understanding Interfaces in Air: The Last Frontier in Atmospheric Chemistry?

Abstract:

Airborne particles are well known to have significant impacts on visibility, health and climate. As a result, being able to predict their formation, composition and properties is critical for the development of effective air pollution control strategies on local to global scales. While a great deal is known about gas phase chemistry in air, less is known about chemistry in condensed phases and even less about “heterogeneous chemistry” at interfaces, yet the latter two are particularly important for understanding airborne particles. Some examples of what we know and what we don’t know about such chemistry will be discussed, with an emphasis on the need for application of a variety fundamental chemical approaches, both experimental and theoretical, to address the key unknowns.

Facutly Host: Dr. Marcelo Guzman

High Resolution Laser Spectroscopy of Radical Containing Complexes and Radical-Radical Reaction Products in Helium Nanodroplets

Dr. Gary Douberly

Department of Chemistry, University of Georgia, Athens, Georgia 30602 USA

Helium nanodroplet isolation (HENDI) is a versatile technique for many forms of molecular spectroscopy.  Helium nanodroplets provide a dissipative medium for studying at 0.4 Kelvin, the structure and dynamics of novel systems such as free-radicals, metal clusters, and molecular clusters.  In this talk, I will discuss our recent use of HENDI and infrared laser spectroscopy to investigate the CH₃ + O₂ and C₃H₃ + O₂ reactions.  HENDI is also used to investigate the effect of the superfluid helium environment on the spectroscopy and dynamics of the OH radical and its complexes with O₂ and C₂H₂. 

Hydrocarbon radicals generated in an effusive pyrolysis source are picked-up by helium droplets and cooled to 0.4 K prior to the addition of single O₂ molecules.  In this experimental configuration, a reaction may occur between sequentially picked-up and cold reactants.  The resulting products of this low temperature reaction are probed spectroscopically downstream from the pick-up zones.  The CH₃ + O₂ reaction leads barrierlessly to the methyl-peroxy radical, and although the droplets must dissipate an energy of ~30 kcal/mol, the infrared spectra reveal a large abundance of droplets containing the cold CH₃O₂ radical.  Theoretical studies have predicted an approximately 2-4 kcal/mol barrier in the entrance channel of the C₃H₃ + O₂ reaction.  Because of this prediction, a weakly bound “entrance channel” C₃H₃--O₂ van-der-Waals complex was expected, given the rapid cooling provided by the dissipative helium environment.  In addition to the trans-acetylenic isomer of the propargyl-peroxy (C₃H₃O₂) radical, we now have experimental evidence for the metastable C₃H₃--O₂ complex.

The fundamental vibrational band of the helium solvated hydroxyl radical (OH) has two sharp Q(3/2) lines.  The splitting is consistent with a fivefold increase in the parity (lambda type) doubling of the ²P_3/2 state in helium droplets relative to the gas phase.  This parity splitting increase is rationalized in terms of the differences in the potential energy surfaces for He-OH(A') and He-OH(A").  Rotationally resolved OH and CH stretching bands of the T-shaped OH-C₂H₂ complex reveal that the electronic angular momentum of OH in the complex is only partially quenched, and to a similar degree as observed in the gas phase.^1,2  This indicates that the helium droplet environment does not significantly affect the electronic intermolecular interactions in OH-C₂H₂.

HO₃ and HOOO-(O₂)_n clusters have also been assembled in helium nanodroplets.  The trans-HOOO isomer is observed and has vibrational band origins within 1 cm^-1 of the gas phase values.^3,4  This supports recent theoretical calculations, which show that the HO + O₂ reaction is barrierless.  Neither of the two other predicted stable isomers, namely cis-HOOO and the hydrogen-bound OH-O₂ species,⁵ were found within a broad survey scan.  HOOO-(O₂)_n clusters grow in to the red of the n₁ band of trans-HOOO as the O₂ pick-up pressure is increased.  HOOO-(O₂)_n cluster bands are resolved up to n=4.  High level ab initio calculations are being carried out to help understand the geometries of these multiple O₂ clusters.

(1)        J. B. Davey, M. E. Greenslade, M. D. Marshall, M. I. Lester, and M. D. Wheeler, J. Chem. Phys. 121, 3009 (2004)

(2)        M. D. Marshall, J. B. Davey, M. E. Greenslade, and M. I. Lester, J. Chem. Phys. 121, 5845 (2004)

(3)        Derro, E. L.; Murray, C.; Sechler, T. D.; Lester, M. I. J. Phys. Chem. A 2007, 111, 11592

(4)        Derro, E. L.; Sechler, T. D.; Murray, C.; Lester, M. I. J. Chem. Phys. 2008, 128.

(5)        Braams, B. J.; Yu, H. G. PCCP 2008, 10, 3150.

For more information on Dr. Douberly and his research, click here.

Faculty Host: Dr. Dong-Sheng Yang

Dr. Gregory Robinson of the University of Georgia will be presenting a seminar entitled Carbene-Stabilization of Highly Reactive Main Group Molecules.

Faculty Host: Dr. David Atwood

Dr. Andrew Pohorille from the National Aeronautics and Space Administration (NASA) will be presenting a seminar entitled The Origins of Protein Functions in Cells.

Facutly Host: Dr. Yinan Wei

Dr. Hyman Hartman of MIT will be presenting a seminar entitled The Origin and Evolution of Photosynthesis.

Abstract:

The origin and evolution of photosynthesis is considered to be the key to the origin of life. This eliminates the need for a soup as the synthesis of the bioorganics are to come from the fixation of carbon dioxide and nitrogen. No soup then no RNA world or Protein world.  Cyanobacteria have been formed by the horizontal transfer of green sulfur bacterial photoreaction center genes by means of a plasmid into a purple photosynthetic bacterium.

The fixation of carbon dioxide is considered to have evolved from a reductive dicarboxylic acid cycle  (Chloroflexus) which was then followed by a reductive tricarboxylic acid cycle (Chlorobium) and  finally by the reductive pentose phosphate cycle (Calvin cycle).

The origin of life is considered to have occurred in a hot spring on the outgassing early earth. The first organisms were self-replicating iron-rich clays which fixed carbon  dioxide into oxalic and other dicarboxylic acids. This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of the hotspring acquiring the ability to fix nitrogen. Finally phosphate was incorporated into the evolving systemwhich allowed the synthesis of nucleotides and phospholipids.

If biosynthesis recapitulates biopoesis, then the synthesis of amino acids preceded  the synthesis of the purine and pyrimidine bases. Furthermore the polymerization of the amino acid thioesters into polypeptides preceded the directed polymerization of amino acid esters by polynucleotides. Thus the origin and evolution of the genetic code is a late development and records the takeover of the clay by RNA.

Faculty Host: Dr. Marcelo Guzman

Dr. Jinjun Liu of the University of Louisville will be presenting a seminar entitled The Methoxy Radical: An Incredible Playground for Hi-resolution Molecular Spectroscopists.

Faculty Host: Dr. Dennis Clouthier