RUI: Phosphorescence Probe of Heme Protein Dynamics

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9417885 Schuh A detailed understanding of the dynamic internal motion of globular proteins is sought because of its importance to a knowledge of the structure/function relationships of proteins as they pertain to fundamental research and to applied aspects of industrial research involving production of protein pharmaceuticals and the logical design of drugs. The principal investigator and students have reported that the phosphorescence of 6-bromo-2-naphthyl sulfate (BNS) is quenched specifically by the heme of heme proteins. The rate constant for quenching, kq, is determined from lifetime measurements of laser-induced phosphorescence and is used to judge the extent to which internal motion of heme proteins makes the heme rings accessible. In this research attempts will be made to substitute larger phosphorescent molecular probes (e.g. 9-bromo-6- phenanthrene sulfate) in place of BNS. Also kq will be measured for several enzymatic and non-enzymatic heme proteins as a function of temperature and solvent conditions. %%% The ultimate goals are to: 1) estimate the size of transient fluctuations in proteins, 2) determine whether there are fundamental differences in the dynamics of enzymatic and non- enzymatic heme proteins, 3) compare the dynamics of native proteins and an important intermediate in protein folding, called the molten globule, 4) gain insight into the accessibility of the hemes in heme protein complexes, and 5) determine whether tertiary structural dynamics of hemoglobin is important to the binding and release of molecular oxygen. ***