Sharon Hammes-Schiffer | |
---|---|
Born | Sharon Hammes-Schiffer May 27, 1966 (age 58) |
Education | Princeton University Stanford |
Known for | Computational chemistry |
Father | Gordon Hammes |
Awards | Willard Gibbs Award (2021) |
Scientific career | |
Fields | Chemistry Biophysical Chemistry Physical Chemistry Materials Chemistry |
Institutions | Yale University |
Website | http://www.hammes-schiffer-group.org/ |
Sharon Hammes-Schiffer (born May 27, 1966) is a physical chemist who has contributed to theoretical and computational chemistry. She is currently the A. Barton Hepburn Professor of Chemistry at Princeton University. [1] She has served as senior editor and deputy editor of the Journal of Physical Chemistry [2] and advisory editor for Theoretical Chemistry Accounts. [3] She is the editor-in-chief of Chemical Reviews . [2] [4]
Hammes-Schiffer studies "chemical reactions in solution, in proteins and at electrochemical interfaces, particularly the transfer of charged particles driving many chemical and biological processes." [5] Her research draws upon the areas of chemistry, physics, biology, and computer science and is significant for the fields of biochemistry, inorganic chemistry, physical chemistry and physical organic chemistry. A theoretician who works with computational models, Hammes-Schiffer blends classical molecular dynamics and quantum mechanics into theories that have direct relevance to a variety of experimental areas. In studying proton, electron and proton coupled electron transfer, Hammes-Schiffer has formulated a general theory of proton-coupled electron transfer reactions that explains the behavior of protons in energy conversion processes. [2] [6] [7] Her research has enhanced the understanding of hydrogen tunneling and protein motion in enzyme catalysis. [3] [8] Her research group has also developed a nuclear-electronic orbital approach that allows scientists to incorporate nuclear quantum effects into electronic structure calculations. [8] Her work has application to a variety of experimental results and has implications for areas such as protein engineering, drug design, [9] catalyst of solar cells, and enzymatic reactions. [5] In 2024, she was elected to the American Philosophical Society. [10]
Daughter of Gordon Hammes, Sharon Hammes-Schiffer completed her B.A. in chemistry at Princeton University in 1988. She completed her Ph.D. in chemistry at Stanford University in 1993 after working with Hans C. Andersen. [11] [2] [3] She then worked with John C. Tully at AT&T Bell Laboratories as a postdoctoral research scientist. [3]
Hammes-Schiffer held positions on the faculty at the University of Notre Dame as Clare Boothe Luce Assistant Professor of Chemistry and Biochemistry (1995–2000) and at Pennsylvania State University (2000–2012). [3] [12] In 2012 she joined the University of Illinois at Urbana-Champaign as Swanlund Professor of Chemistry, [9] where she remained until 2017. [13] Since then, she has led the Hammes-Schiffer Research Group at Yale University, where she was named John Gamble Kirkwood Professor of Chemistry in 2018, and Sterling Professor of Chemistry in 2021. [14] Starting January 2024, she will join the faculty at Princeton University. [15] Hammes-Schiffer is an author or co-author on nearly 200 papers, and has given more than 200 invited talks. [16]
Hammes-Schiffer's work delves primarily into three separate areas of chemistry: Proton-coupled electron transfer (PCET), Enzymatic Processes, and the Nuclear-Electronic Orbital method. [17] A part of this research engages in the study of the Kinetic isotope effect, a difference in the reaction rate of a chemical based on what isotope is present.
The application of her work in PCET has elucidated the nature of various chemical mechanisms and led to her temperature dependence model of PCET rates. [18] [19] One such process, Quinol Oxidation, studied the Kinetic isotope effect on Ubiquinol and Plastoquinol with regards to temperature, finding that the free energy of activation is greater for hydrogen than for deuterium, meaning the reaction is slower for hydrogen and therefore irreversible, if specific conditions are satisfied. [20] This finding has since been used by other investigators to reinforce the notion that reactions may or may not be unidirectional by influencing reaction rates with the kinetic isotope effect. [21] Additionally, her study of PCET in Iron Bi-imidazoline complexes has refined common comprehension of PCET, having proven her theory that electron transfer rate increases under the kinetic isotope effect as "the proton transfer distance increases and the electron transfer distance decreases." [22] These mechanisms have helped support the research of other PCET studies, with her main PCET paper, "Theoretical Studies of Proton-Coupled Electron Transfer Reactions", [18] having been cited over 90 times by papers ranging from studying protein motion to enzyme dynamics. [23]
Hammes-Schiffer studies the effects of quantum tunnelling and hydrogen bonding on enzymatic reactions. Her work on Soybean Lipoxygenase-1 changed common perception of a previously proposed tunneling region diagram, [24] finding that the temperature dependence of KIEs are inversely proportional to each other and that active environmental dynamics leads to less of the KIE and promotes catalysis. [25] This finding should be applicable to any other enzymes which can transfer a proton due to the fact that there aren't as many enzymatic options for non-ionic transfer of a proton and therefore tunneling must be used throughout the process. [25]
Hammes-Schiffer has also pioneered work in what she calls the Nuclear-electronic orbital method (NEO) which allows for a more accurate estimate of nuclear properties such as density, geometry, frequencies, electronic coupling, and nuclear motions. [26] As described in her paper, "Incorporation of Nuclear Quantum effects in electronic structure," Radial basis function kernel, a gaussian algorithm used to support vector machines, is applied to determine electronic and molecular orbitals. The NEO approach is specifically applicable in determining the exact mechanisms of hydrogen transfer reactions while accounting for other variables such as quantum tunneling and zero point energy. Hammes-Schiffer claims that the NEO approach is significantly advantageous over other methods that incorporate nuclear quantum effects because of the method's ability to calculate vibrational states, its avoidance of Born–Oppenheimer approximation and its apparent and inherent incorporation of quantum effects. [27]
In her study, published in September 2016, Hammes-Schiffer contributed towards discovering the effects of the active site of the magnesium ion in the Scissile Phosphate cofactor complex. She discovered that rather than the magnesium ion lying in the center of the complex, the ion lies in a separate site, termed the Hoogsteen Face, where it lowers the pKa of the complex in order to facilitate a deprotonation reaction necessary for a self-cleavage reaction. [28]
Hammes-Schiffer is a Fellow of the American Physical Society (2010), the American Chemical Society (2011), the American Academy of Arts and Sciences (2012), the American Association for the Advancement of Science (2013), the National Academy of Sciences (2013), and the Biophysical Society (2015). [11] She was elected as a member of the International Academy of Quantum Molecular Science in 2014. [5] [7] [8]
Hammes-Schiffer has received a number of awards, including the following:
Atoms are the basic particles of the chemical elements. An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper. Atoms with the same number of protons but a different number of neutrons are called isotopes of the same element.
Tennessine is a synthetic chemical element; it has symbol Ts and atomic number 117. It has the second-highest atomic number and joint-highest atomic mass of all known elements and is the penultimate element of the 7th period of the periodic table. It is named after the U.S. state of Tennessee, where key research institutions involved in its discovery are located.
In physical organic chemistry, a kinetic isotope effect (KIE) is the change in the reaction rate of a chemical reaction when one of the atoms in the reactants is replaced by one of its isotopes. Formally, it is the ratio of rate constants for the reactions involving the light (kL) and the heavy (kH) isotopically substituted reactants (isotopologues): KIE = kL/kH.
2-Pyridone is an organic compound with the formula C
5H
4NH(O). It is a colourless solid. It is well known to form hydrogen bonded dimers and it is also a classic case of a compound that exists as tautomers.
Enzyme catalysis is the increase in the rate of a process by an "enzyme", a biological molecule. Most enzymes are proteins, and most such processes are chemical reactions. Within the enzyme, generally catalysis occurs at a localized site, called the active site.
The Willard Gibbs Award, presented by the Chicago Section of the American Chemical Society, was established in 1910 by William A. Converse (1862–1940), a former Chairman and Secretary of the Chicago Section of the society and named for Professor Josiah Willard Gibbs (1839–1903) of Yale University. Gibbs, whose formulation of the Phase Rule founded a new science, is considered by many to be the only American-born scientist whose discoveries are as fundamental in nature as those of Newton and Galileo.
Physical organic chemistry, a term coined by Louis Hammett in 1940, refers to a discipline of organic chemistry that focuses on the relationship between chemical structures and reactivity, in particular, applying experimental tools of physical chemistry to the study of organic molecules. Specific focal points of study include the rates of organic reactions, the relative chemical stabilities of the starting materials, reactive intermediates, transition states, and products of chemical reactions, and non-covalent aspects of solvation and molecular interactions that influence chemical reactivity. Such studies provide theoretical and practical frameworks to understand how changes in structure in solution or solid-state contexts impact reaction mechanism and rate for each organic reaction of interest.
Quantum biology is the study of applications of quantum mechanics and theoretical chemistry to aspects of biology that cannot be accurately described by the classical laws of physics. An understanding of fundamental quantum interactions is important because they determine the properties of the next level of organization in biological systems.
A Proton-coupled electron transfer (PCET) is a chemical reaction that involves the transfer of electrons and protons from one atom to another. The term was originally coined for single proton, single electron processes that are concerted, but the definition has relaxed to include many related processes. Reactions that involve the concerted shift of a single electron and a single proton are often called Concerted Proton-Electron Transfer or CPET.
A diffusion-limited enzyme catalyses a reaction so efficiently that the rate limiting step is that of substrate diffusion into the active site, or product diffusion out. This is also known as kinetic perfection or catalytic perfection. Since the rate of catalysis of such enzymes is set by the diffusion-controlled reaction, it therefore represents an intrinsic, physical constraint on evolution. Diffusion limited perfect enzymes are very rare. Most enzymes catalyse their reactions to a rate that is 1,000-10,000 times slower than this limit. This is due to both the chemical limitations of difficult reactions, and the evolutionary limitations that such high reaction rates do not confer any extra fitness.
Nancy Makri is the Edward William and Jane Marr Gutgsell Endowed Professor of Chemistry and Physics at the University of Illinois Urbana–Champaign, where she is the principal investigator of the Makri Research Group for the theoretical understanding of condensed phase quantum dynamics. She studies theoretical quantum dynamics of polyatomic systems, and has developed methods for long-time numerical path integral simulations of quantum dissipative systems.
Jillian Lee Dempsey is an American inorganic chemist and the Bowman and Gordon Gray Distinguished Term Professor at the University of North Carolina at Chapel Hill. Currently, her work focuses on proton-coupled electron transfer, charge transfer events, and quantum dots. She is the recipient of numerous awards for rising stars of chemistry, including most recently a 2016 Alfred P. Sloan Research Fellowship and a 2016 Air Force's Young Investigator Research Program (YIP).
A field effect is the polarization of a molecule through space. The effect is a result of an electric field produced by charge localization in a molecule. This field, which is substituent and conformation dependent, can influence structure and reactivity by manipulating the location of electron density in bonds and/or the overall molecule. The polarization of a molecule through its bonds is a separate phenomenon known as induction. Field effects are relatively weak, and diminish rapidly with distance, but have still been found to alter molecular properties such as acidity.
Dr. Dan Thomas Major is a Professor of Chemistry at Bar Ilan University specializing in Computational Chemistry.
Daniel Kwabena Dakwa Bediako is a Ghanaian-British chemist. He is currently assistant professor at the University of California, Berkeley, and is the Cupola Era Professor in the college of chemistry. His research considers charge transport and interfacial charge transfer in two-dimensional materials and heterostructures. He is also a member of the Editorial Advisory Board of the Journal of the American Chemical Society (JACS).
In stable isotope geochemistry, the Urey–Bigeleisen–Mayer equation, also known as the Bigeleisen–Mayer equation or the Urey model, is a model describing the approximate equilibrium isotope fractionation in an isotope exchange reaction. While the equation itself can be written in numerous forms, it is generally presented as a ratio of partition functions of the isotopic molecules involved in a given reaction. The Urey–Bigeleisen–Mayer equation is widely applied in the fields of quantum chemistry and geochemistry and is often modified or paired with other quantum chemical modelling methods to improve accuracy and precision and reduce the computational cost of calculations.
Intrinsic bond orbitals (IBO) are localized molecular orbitals giving exact and non-empirical representations of wave functions. They are obtained by unitary transformation and form an orthogonal set of orbitals localized on a minimal number of atoms. IBOs present an intuitive and unbiased interpretation of chemical bonding with naturally arising Lewis structures. For this reason IBOs have been successfully employed for the elucidation of molecular structures and electron flow along the intrinsic reaction coordinate (IRC). IBOs have also found application as Wannier functions in the study of solids.
Frances Ann Walker was an American chemist known for her work on heme protein chemistry. She was an elected fellow of the American Association for the Advancement of Science and the American Chemical Society.
Suzanne Cathleen Bart an American chemist who is a professor of inorganic chemistry at Purdue University. Her group's research focuses on actinide organometallic chemistry, and especially the characterization of low-valent organouranium complexes, actinide complexes with redox-active ligands, and discovery of new reactions that utilize these compounds. Bart's research has applications in the development of carbon-neutral fuel sources and the remediation of polluted sites.