Studies On Intreaction Of Nitrosyl Iron-Sulfur Clusters With Biomacromolecules

Nitric oxide(NO)molecules are involved in various important physiological processes.It is a fat-soluble gas that plays an important role of messenger molecules in the cerebral vasculature,immune system,nervous system,reproductive system and cancer system.Its concentration is closely related with its function.The amount of NO provided by the healthy organism itself can maintain the normal physiological function of the organism.When the physiological level lacks NO,it causes cardiovascular diseases such as hypertension and arteriosclerosis.Therefore,it is necessary to find an external nitric oxide donor.Compared with other types of NO donors,iron nitrosyl complexes can produce NO controlled by external physical and chemical stimuli.The nitrosyl iron-sulfur clusters known as Roussin black salt(RBS,(Me4N)[Fe4S3(NO)7])and Roussin red salt(RRS,(Me4N)2[Fe2S2(NO)4]),with photo irradiation can control the release of nitric oxide.In addition,these nitrosyl iron complexes also affect the storage and transport of nitric oxide in organisms and the control of enzymes.This study provides a new basis for further understanding of the possible physiological and pharmacological mechanisms for nitrosyl iron-sulfur clusters.In this paper,two kinds of iron-sulfur nitrosyl clusters(Me4N)[Fe4S3(NO)7] and(Me4N)2[Fe2S2(NO)4] were synthesized and confirmed by X-ray single crystal diffraction technique.The compounds were characterized by UV-Vis absorption spectroscopy and infrared spectroscopy.The physical and chemical properties of these clusters were compared;kinetic stability of complexes was investigated by detecting changes in the infrared spectrum of complexes.And UV-visible absorption spectroscopy,fluorescence spectroscopy and fluorescence lifetime were used to study the binding of CT-DNA and complexes,and the binding mechanism was analyzed.The agarose gel electrophoresis experiment was carried out to study the photocleavage process of the plasmid PBR322 DNA and its mechanism.The interaction between human serum albumin and complexes was studied by UV-visible absorption spectrum and fluorescence spectrum.The fluorescence quenching mechanism was studied by fluorescence lifetime experiment.This study provides a new basis for understanding the possible physiological and pharmacological mechanisms of nitrosyl iron sulfide clusters.The main contents of this paper mainly include six parts:In chapter 1,the background and purpose of this work,the structure and function of common iron-sulfur clusters and the properties of some nitrosyl iron sulfide clusters are briefly introduced in this chapter.In chapter 2,two nitrosyl iron-sulfide clusters(Me4N)[Fe4S3(NO)7] and(Me4N)2[Fe2S2(NO)4] were synthesized,and compared their physical and chemical properties.X-ray single crystal diffraction confirmed the structure of the complexes.The UV-visible absorption spectrum was used to know the type of electronic transition in compounds.The chemical bonds and functional groups of the complexes were detected by IR.In chapter 3,the kinetic stability of complexes was studied by infrared spectroscopy.Compared with(Me4N)[Fe4S3(NO)7],the(Me4N)2[Fe2S2(NO)4]is more stable,the solvent and light will affect the stability of the complexes.In chapter 4,the interaction between the complex and the DNA was studied using UV-visible absorption spectrum,fluorescence spectrum and agarose gel electrophoresis.The experimental results showed that the complexes were embedded in the DNA double-helix structure to bind with DNA,and destroy double-helical structure of DNA.The fluorescence lifetime test shows that the binding of complexes to DNA occurs in the ground state of DNA,and the fluorescence of DNA is quenched by static quenching.The fluorescence data also provides the binding constant such as the number of sites of them.The photocleavage process of plasmid p BR322 DNA and its mechanism were studied by agarose gel electrophoresis.In chapter 5,the interaction between the complex and human serum albumin was studied by UV-Vis absorption spectrum and fluorescence spectrum.The complex interact with human serum albumin and changed conformation of human serum albumin.Fluorescence quenching mechanism was obtained by fluorescence lifetime experiment,and their quenching mechanism is combination of static and dynamic quenching.In chapter 6,all the works and future plan were summarized.