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Pertussis Toxin Time–Resolved Absorption and Resonance FT–IR and Raman Biospectroscopy and Density Functional Theory (DFT) Investigation of Vibronic–Mode Coupling Structure in Vibrational Spectra Analysis

  • Alireza Heidari Faculty of Chemistry, California South University, 14731 Comet St. Irvine, CA 92604, USA
  • Jennifer Esposito Faculty of Chemistry, California South University, 14731 Comet St. Irvine, CA 92604, USA
  • Angela Caissutti Faculty of Chemistry, California South University, 14731 Comet St. Irvine, CA 92604, USA

Abstract

Pertussis toxin (PT) is a protein–based AB5–type exotoxin produced by the bacterium Bordetella pertussis, which causes whooping cough. PT is involved in the colonization of the respiratory tract and the establishment of infection. Research suggests PT may have a therapeutic role in treating a number of common human ailments, including hypertension, viral infection, and autoimmunity. Parameters such as FT­–IR and Raman vibrational wavelengths and intensities for single crystal Pertussis Toxin are calculated using density functional theory and were compared with empirical results. The investigation about vibrational spectrum of cycle dimers in crystal with carboxyl groups from each molecule of acid was shown that it leads to create Hydrogen bounds for adjacent molecules. The current study aimed to investigate the possibility of simulating the empirical values. Analysis of vibrational spectrum of Pertussis Toxin is performed based on theoretical simulation and FT–IR empirical spectrum and Raman empirical spectrum using density functional theory in levels of F/6–31G*, HF/6–31++G**, MP2/6–31G, MP2/6–31++G**, BLYP/6–31G, BLYP/6–31++G**, B3LYP/6–31G and B3LYP6–31–HEG**. Vibration modes of methylene, carboxyl acid and phenyl cycle are separately investigated. The obtained values confirm high accuracy and validity of results obtained from calculations.

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