Photo Properties of Bio Molecules

Abstract

The properties of microscopic systems have been explained on the basis of quantum physics. The biological molecules viz. proteins and amino acids are studied at molecular level by using different quantum methods such as CASSCF, NEVPT2, DFT, TDDFT, MP2, and HF methods. These methods are efficient in computing the complex chemical and biological molecules by using the power of computers. These methods give accurate and systematic treatment of electron correlation for both the ground and excited states in comparison to classical models. The interaction of biological molecules with electromagnetic radiation is fundamentally important. The ultraviolet radiation (UV) can damage structurally to molecules because of its high energy. It causes to lose the stability of the molecules. In chapter three, the photo stability of the basic amino acid i.e., two glycine molecules has been studied in gaseous and dielectric medium. The effect of dielectric medium, to the photostability of two glycine molecules is investigated. The minimum energy path MEPs of glycine dimmers are computed that shows glycine dimmers are highly photo stable in water as dielectric media as comparison to vacuum. newlineThe retinal chromophore plays a crucial role in the absorption of light in proteins. It triggers the response of protein to exposure of light. In chapter four, the spectral shift in absorption and emission spectra has been investigated in dielectric medium. The water is used as dielectric medium, in which absorption peaks are shifted in surrounding environment and photoisomerization paths are computed though protonated Schiff base PSB linkage along the redundant coordinates. The absorption peak in dielectric media is shifted towards the larger wavelength. The photosynthesis in plant, vision process in animals, and fluorescent state in jellyfish are important processes, which are investigated by theoretical method. The properties of biological system at molecular and atomic level are also studied. In chapter 5, the photo induced reactions are studied to understand the photo cycle of green fluoresce protein GFP. The different chemical parameters as dihedral angles, bond lengths, and angles between three atoms of the molecules are computed. The emission of fluorescent spectra has been computed, and results are discussed. The phosphoresce property of the GFP molecule is also analyzed. newline newline