Study of IR Spectrum of the 17b-Estradiol using Quantum-Chemical Density Functional Theory

Introduction The vibration motion of nuclei in molecules is one of the most important factors which conditions physico-chemical properties and reactivity of substances. The solution for classical equations subject to force filed, discovered from the Schrödinger’s equation in adiabatic approximation, allows determining the forms of vibration of polyatomic molecules as well as their frequencies. The use of these methods in biochemistry of steroid hormones seems the most up to date, as it supplies the possibility to understand the interaction of steroid hormones with the receptors at the microscopic level. The estrogens are considered to be important regulators of mammalian reproductive function [1, 2]. They provide embryo formation and development. Biochemical effects of estrogens are realized as a result of their direct influence on the chromosomal apparatus of the cell at the expense of gene expression change and the stimulation of RNA synthesis rate (the details of this process are still not clear) [2]. On penetrating the cell membrane the estrogens are initially bound with cytoplasmic receptors, which causes their activation, necessary for their penetration into the nucleus. The process of gene expression begins with transcription, i.e. with the formation of the mRNA precursors and the formation of biologically active mRNAs, which then move to cytoplasm. The mRNA translation on ribosomes results in the synthesis of specific proteins of the cell, which gives grounds for the statement that the cytosolic or direct action mechanism is specific for estrogens. The study of the reception of steroid hormones is considered to be one of the most important challenges of modern biology and medicine [1]. Especially, the structure of estrogen receptors as well as their interaction with 17b-estradiol represent a great interest since the cancer diagnostics and treatment are directly