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Emissive Enhancement of the Singlet Oxygen Chemiluminescence Probe after Binding to Bovine Serum Albumin.

Authors
  • Miranda-Apodaca, Jon1
  • Hananya, Nir2
  • Velázquez-Campoy, Adrián3, 4, 5, 6, 7
  • Shabat, Doron2
  • Arellano, Juan B8
  • 1 Departamento de Estrés Abiótico, Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), 37008 Salamanca, Spain. , (Spain)
  • 2 School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel. , (Israel)
  • 3 Institute of Biocomputation and Physics of Complex Systems (BIFI), Joint Units IQFR-CSIC-BIFI, and GBsC-CSIC-BIFI, Universidad de Zaragoza, 50018 Zaragoza, Spain. , (Spain)
  • 4 Department of Biochemistry and Molecular and Cell Biology, Universidad de Zaragoza, 50009 Zaragoza, Spain. , (Spain)
  • 5 Aragon Institute for Health Research (IIS-Aragon), 50009 Zaragoza, Spain. , (Spain)
  • 6 Biomedical Research Networking Center in Digestive and Hepatic Diseases (CIBERehd), 28029 Madrid, Spain. , (Spain)
  • 7 Fundación ARAID, Government of Aragon, 50018 Zaragoza, Spain. , (Spain)
  • 8 Departamento de Estrés Abiótico, Instituto de Recursos Naturales y Agrobiología de Salamanca (IRNASA-CSIC), 37008 Salamanca, Spain. [email protected] , (Spain)
Type
Published Article
Journal
Molecules
Publisher
MDPI AG
Publication Date
Jul 01, 2019
Volume
24
Issue
13
Identifiers
DOI: 10.3390/molecules24132422
PMID: 31266247
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

A chemiluminescence probe for singlet oxygen 1O2 (SOCL) was investigated in phosphate buffer saline (PBS), either in the absence of proteins or containing bovine serum albumin (BSA). In the protein-free PBS, the reactivity of SOCL for methylene blue (MB)-photosensitized 1O2 was found to be moderate or low. The reaction yield increased with temperature and/or concentration of dissolved molecular oxygen. Unexpectedly, the presence of BSA boosted both the emissive nature and the thermal stability of the phenoxy-dioxetane intermediate formed in the chemiexcitation pathway. Isothermal titration calorimetry showed that SOCL has a moderate binding affinity for BSA and that entropy forces drive the formation of the SOCL-BSA complex. A model with two identical and independent binding sites was used to fit the binding isotherm data. Co-operative binding was observed when MB was present. Local viscosity factors and/or conformational restrictions of the BSA-bound SOCL phenoxy-dioxetane were proposed to contribute to the formation of the highly emissive benzoate ester during the chemically initiated electron exchange luminescence (CIEEL) process. These results led us to conclude that hydrophobic interactions of the SOCL with proteins can modify the emissive nature of its phenoxy-dioxetane, which should be taken into account when using SOCL or its cell-penetrating peptide derivative in living cells.

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