CAREER: Ultrafast hydrogen-bond dynamics in crowded, heterogeneous environments

点击翻译按钮获取中文摘要

With funding by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Carlos Baiz of the University of Texas at Austin is investigating the structure and motions of biological molecules in "crowded" environments. Biological molecules (biomolecules) like proteins and DNA can contain many atoms (thousands!). This means that their structures and internal motions (bending, twisting, folding) can be very complicated and hard to predict. In order to understand biomolecules, chemists have studied them in dilute solution, in other words, under conditions where they are interacting with surrounding water molecules, but not other large biomolecules. It has recently become evident that findings from these studies in dilute solution may not be representative of biological environments. In real living cells, biomolecules exist and function in crowded environments, often assembled together to form membranes, enzyme complexes, and organelles. What are the actual behaviors of biomolecules in real, crowded conditions? Professor Baiz and his students are using a technique called time-resolved, two-dimensional, infrared spectroscopy (2D IR) to study the structure and motions of molecules in more realistic, crowded environments. In order to help interpret the complicated 2D IR data, Professor Baiz is developing computer models for the crowded systems. Together, the experimental and computational studies are forming connections among molecular structure, environments, and dynamics to rationalize the mechanisms of protein interactions in the cell. Through this project, Professor Baiz and his students are providing insights into how living systems function at the molecular level. The research may also lead to new cryoprotectant technologies (cryoprotectants are chemical substances that hinder the formation of detrimental ice crystals in cells when they are frozen). The students engaged in this project are gaining valuable skills and experience in cutting edge laser optics technology as well as in the computer simulation of molecular systems. The broader impacts of this project aim to increase representation from minority students in the Chemistry graduate program at the University of Texas at Austin through organized visit days for underrepresented students across the southwestern states. These efforts seek to boost diversity among the future science and technology workforce.This project focuses on mapping the ultrafast hydrogen-bond dynamics of small molecules that mimic the protein backbone in solutions with crowding agents such as polymers and proteins to characterize the effects of crowding and confinement on solvation dynamics. Ultrafast two-dimensional infrared spectroscopy is used to extract frequency-frequency correlation functions, which are directly compared to molecular dynamics simulations. Structure-based infrared maps are used to generate spectra from molecular dynamics trajectories, and thus provide a direct connection between experiments and simulations. Vibrational probes, including thiocyanates, are used to access the solvation environments on the surface of proteins to understand the effect of protein polarity and electrostatics on local hydrogen-bond networks.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.