Porphyrin-Mediated Photoinduced Conformational Changes to Albumin

POSTER

Abstract

Many biological and nonbiological uses of protoporphyrin-IX (PPIX) depend on its ability to bind large macromolecules such as human serum albumin (HSA). HSA is both biomedically and technologically relevant to PPIX (free base and metal), and its binding site for PPIX-derivatives is well established. The irradiation of PPIX noncovalently bound to BetaLactoglobulin (BLG) is known to cause protein conformational changes that are pH-dependent due to BLG's intrinsic conformational transitions. These processes have not been extensively studied in nonphysiological pH conditions for FePPIX or PPIX bound to HSA. This study implemented a combination of optical and computational methods to compare binding characteristics of hemin and PPIX to HSA as well as structural effects of lowdose irradiation of the ligand on the protein. Spectroscopic data suggests that irradiation of the Soret band of PPIX bound to HSA is capable of modifying the globular protein structure by direct charge transfer between the porphyrin and the binding site at both physiological and acidic pH confirmations. Computational docking simulations predict lower free energy of binding for PPIX than for heme.

Authors

  • Sarah Rozinek

    UTSA

  • Allan Headley

    Texas A\&M, Sam Houston State University, Southern Methodist University, Dept of Physics, Texas Tech University, Depts of Cell Physiology and Molecular Biophysics, Texas Tech University HSC, Texas Tech University, Lee College, Texas A\&M University, Texas A\&M Univ.-Commerce, University of North Texas, Texas A\&M University and Princeton University, Princeton University, The University of North Texas, University of Texas at Austin, Center for High Energy Density Science, University of Texas at Austin, Institute for Fusion Studies, University of Texas at Austin, UT Arlington, Stephen F. Austin State University, Texas A&M University--Commerce, University of Texas at Dallas, University of Texas at El Paso, Department of Physics, The University of Texas at Dallas, Department of Physics and Astronomy, Francis Marion University, University of Texas at Brownsville, Texas State University--San Marcos, UTSA, Northwestern University, Rice University, Abilene Christian University, Texas Southern University, Department of Physics, Southern Methodist University, Dallas, Texas A\&M University Cyclotron Institute, Sciprint.org, University of Texas MD Anderson Cancer Center, University of Texas at San Antonio, Paschal High School, Fort Worth, TX, Department d'Enginyeria Electronica, Universitat Autonoma de Barcelona, Department of Physics, Texas State University at San Marcos, Texas State University at San Marcos, Angelo State University, Texas State University-San Marcos, Department of Surgery, The University of Texas Southwestern Medical Center, Dallas, TX 75390, Department of Medicine, Baylor College of Medicine, Department of Bioengineering, Rice University, Department of Physics and Astronomy, Rice University, Department of Surgery, University of Texas Southwestern Medical Center, University of Texas at Dallas, Physics, Viginia State University, Jefferson Laboratory, Trinity University, LIGO, UTB-TSC, Mount Holyoke College, Texas A&M University, Electrical and Computer Engineering, TAMU, American Institute of Physics, University of Texas at Arlington, Texas Christian University, Fort Worth, TX, University of Pennsylvania, Philadelphia, PA, University of Missouri-Columbia, Columbia, MO, Paine College, Augusta, GA, Univ. of Edinburgh, INFN-LNS, INFN LNS CATANIA ITALY, Arkansas Technical University, AR, USA, Cyclotron Institute Texas A\&M University College Station Usa, and Heather Galloway, Texas State University--San Marcos