Mechanistic Studies of Catalytic Multifunctional Globins Using Advanced Structural Methods

点击翻译按钮获取中文摘要

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Drs. Reza Ghiladi and Stefan Franzen from North Carolina State University to investigate iron containing proteins, specifically heme-iron proteins, from marine environments as models for understanding their function in mammalian systems. Heme-iron proteins are found universally throughout nature, and they perform important biological roles that are the foundation for nearly all living systems. Notable examples of heme-iron proteins include the oxygen carrier in blood, hemoglobin, and the detoxifying enzymes known as cytochromes P450 found in the liver. While the importance of heme proteins has been recognized by the chemical and biological communities for many years, it is challenging to apply the latest emerging techniques to study their function. The use of related but simpler marine hemoglobin provides an avenue to develop these methods while also gaining a better understanding the diverse roles of heme proteins in biology and chemistry. The proposed experimental procedures help characterize at the atomic level how molecules will bind to these important proteins and alter their function. This pursuit allows graduate students to acquire specialized training in both high resolution X-ray and neutron crystallography, as well as in time-resolved structural methods. The fast timescale methods are cutting-edge techniques that push the limits of what is experimentally obtainable for studying how enzymes perform their tasks within living systems. This project is integrated with the "Creating STARS" outreach program to provide rural middle school science classrooms with visits, demonstrations, lectures, and lessons plans covering the chemistry/life interface. The project is also engaging both domestic (Oak Ridge National Laboratory) and international (University of Essex and the Polish Academy of Science) partners in data acquisition and analysis.This research project seeks to identify a unique set of structural interactions that occur upon substrate binding to the enzyme dehaloperoxidase, thereby controlling the kinetics and reactivity of the heme intermediates, and ultimately a discrimination in enzymatic activity specific to the bound substrate. Rapid-freeze-quench, caged O2-carrier photolysis, and CO flash photolysis techniques are to be conducted to enable the trapping of intermediates and to initiate time-resolved studies to characterize in unprecedented detail these mechanistically important intermediates relevant to catalytic turnover. The relationship of dehaloperoxidase to other hemoglobins, peroxidases and peroxygenases establishes new paradigms of protein structure-function relationships relevant to multifunctional proteins, complementing those established for monofunctional enzymes. Information from this study has the potential to advance the understanding of catalytic globins, determine the structural features that lead to activity differentiation across heme proteins (and across metalloenzymes more generally), and enable the comparison of the structure-function correlation in enzymes of marine origin in relation to those from terrestrial or bacterial sources.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.