Chemistry Education and Protein Dynamics

Lynmarie Posey

Associate Professor

61 CEM

517-353-1193



Primary Research Area

Chemical Education (CE)

Other Area(s) of Interest

Biological (Bi)

Physical (Ph)

Research

(Research Description PDF)

Knowledge of molecular-scale inter­actions is central to understanding reactivity, energy, and dynamics in chemical systems for both novices and experts. Exploration of molecular-scale interactions is a theme that is common to Dr. Posey’s research in chemistry education and experimental physical chemistry.

A Developmental Chemistry Curriculum for Underprepared Students – In 2012, the President’s Council of Advisors on Science and Technology (PCAST) reported that one million additional college graduates with STEM degrees would be needed over the next 10 years to meet the anticipated demand for technically skilled workers. Unfortunately, many students interested in pursuing STEM careers enter college without the background and skills required to succeed in general chemistry, which is typically the first of the gateway science courses required in STEM degree programs. In fact, fewer than 40% of the students who enter college as STEM majors graduate with a STEM degree.

Developmental chemistry courses designed to serve the needs of underprepared students have typically focused on drilling students in algorithmic problem-solving. In contrast, we are investigating a new approach to supporting these students that is built around a learning progression for a core idea in chemistry, the structure and properties of matter. Learning progressions describe possible pathways to increasingly complex and scientifically correct understanding within a domain and are grounded in what is known about learning as a developmental process. They carefully scaffold student learning on existing knowledge to build understanding that is transferrable and robust. To further support students in building and using their knowledge, we blend scientific practices (using models, constructing scientific explanations, and applying mathematical thinking) with content in instruction and student activities. We are studying the impact of this novel approach to developmental chemistry on student motivation, self-efficacy, science identity, and success in general chemistry.

Our early work has shown that even when scientific practices largely replace traditional chemistry calculations in a developmental chemistry course, student success strongly correlates with success in mathematics. Furthermore, student interviews have revealed that students see little connection between the mathematics they use in chemistry and the mathematics that they learn in their mathematics courses. We have initiated a collaboration with a mathematics education researcher to study connections between mathematics and chemistry learning and to explore strategies to build students’ ability to apply mathematics in a scientific context and to help them see the utility of mathematics in science.

Slow Protein Dynamics – Proteins exhibit richly textured energy landscapes near the native fold with barriers that can be surmounted by structural fluctuations at physiological temperatures. Numerous low-energy barriers near the native fold result in an ensemble of conformational states with equilibrium fluctuations posited to play a significant role in both biological function and creation of the misfolded states implicated in diseases including Alzheimer’s, Parkinson’s, Creutzfeldt-Jakob, and bovine spongiform encephalopathy.

Many of the dynamic processes in proteins that are relevant to biological function and misfolding involve collective, large-amplitude motions that occur on relatively long timescales (μs and longer). The long-lived triplet states responsible for phosphorescence emission permit us to extend the time window for electronic emission spectroscopy to a time regime that is relevant to physiologically important slow protein motions. We have demonstrated that time-resolved phosphorescence spectroscopy and the phosphorescence dynamic Stokes shift can be used to characterize timescales for large-amplitude motions near the native fold in proteins. This approach is being used to measure barrier heights near the native fold and to study the influence of the hydration layer on protein dynamics.

Time-resolved phosphorescence spectra from ZnII-substituted cytochrome c exhibit a dynamic Stokes shift response arising from protein dynamics on the μs timescale.

Selected Publications

Core Ideas and Topics: Building Up or Drilling Down?, M. M. Cooper, L. A. Posey, and S. M. Underwood, J. Chem. Educ. 2017, 94, 541–548.

Characterizing College Science Assessments: The Three-Dimensional Learning Assessment Protocol, J. T. Laverty, S. M. Underwood, R. L. Matz, L. A. Posey, J. H. Carmel, M. D. Caballero, C. L. Fata- Hartley, D. Ebert-May, S. E. Jardeleza, and M. M. Cooper, PLoS ONE 2016, 11, e0162333.

Challenge Faculty to Transform STEM Learning: Focus on Core Ideas, Crosscutting Concepts, and Scientific Practices, M. M. Cooper, M. D. Caballero, D. Ebert-May, C. L. Fata-Hartley, S. E. Jardeleza, J. S. Krajcik, J. T. Laverty, R. L. Matz, L. A. Posey, S. M. Underwood, Science 2015, 350, 281-282.

Dynamic Stokes Shift of the Time-resolved Phosphorescence Spectrum of ZnII-substituted Cytochrome c, L. A. Posey, R. J. Hendricks, and W. F. Beck, J. Phys. Chem. B 2012, 117, 15926–15934.

CV

B.S., 1984, David­son College

Ph.D., 1989, Yale Univ.

NSF Post­doctoral Research Fellow, 1989-1991, Stanford Univ.

Assistant Professor, 1991-1998, Associate Professor, 1998, Vanderbilt Univ.

Awards/Honors

2016 Faculty Teaching Prize Michigan State University (College of Natural Science)
1989 Ph.D. Yale University
1989 - 1991 Postdoctoral Research Fellow National Science Foundation (Stanford University)
1984 Bachelor of Science Davidson College