Anthrax 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

Abstract

Anthrax toxin is a three-protein exotoxin that is secreted by the bacterium's virulent strains, the anthrax causative agent Bacillus anthracis. Harry Smith first found the toxin in 1954. Anthrax toxin consists of a protein called a protective antigen (PA) binding cell protein and two enzyme parts called an edema factor (EF) and a deadly factor (LF). These three protein components act together to impart their physiological effects. Assembled complexes containing the toxin components are endocytosed. In the endosome, the enzymatic components of the toxin translocate into the cytoplasm of a target cell. Once in the cytosol, the enzymatic components of the toxin disrupt various immune cell functions, namely cellular signaling and cell migration. The toxin may even induce cell lysis, as is observed for macrophage cells. Anthrax toxin enables the bacteria to escape, proliferate, and eventually destroy the host animal, the immune system. Anthrax toxin research also offers insight into the generation of macromolecular assemblies and the translocation of proteins, pores, endocytosis and other biochemical procedures. Parameters such as FT-IR and Raman vibrational wavelengths and intensities for single crystal Anthrax 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 has 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 Anthrax 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.

Keywords: Vibronic structure, vibrational spectra analysis, Density Functional Theory (DFT), anthrax toxin, non-focal functions of Becke, correlation functions of Lee-Yang-Parr, time–resolved absorption and resonance, FT-IR, Raman biospectroscopy

Cite this Article Alireza Heidari, Jennifer Esposito, Angela Caissutti. Anthrax 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. Research & Reviews: Journal of Computational Biology. 2019; 8(2): 23–51p.