Regulation Of Nucleic Acid On Copper-zinc Superoxide Dismutase Aggregation

Amyotrophic lateral sclerosis (ALS) is one of neurodegenerative diseases, it’s relation to the aggregation of the misfolding SOD1is found by research, it’s aggregation, oligomers and soluble oligomers, is presumed cytotoxic species. The structure and nature changes of SOD1itself or due to external environment may be the main cause of SOD1aggregation, based on our group research foundation on the interaction between DNA and SOD1, the interaction between them is studied from various types of SOD1aggregation in this paper, Seeking to establish a relationship between the aggregate type formed by different structures DNA regulating SOD1and Cytotoxicity. The interaction of DNA with SOD1is researched primarily by isothermal titration calorimetry, circular dichroism, ANS fluorescence spectra, ultraviolet absorption spectrum, right angle light scattering, inverted fluorescence microscope, transmission electron microscopy and cytotoxicity by MTT etc. And the results are as follows:(1) Isothermal titration calorimetry shows that the interaction of the various DNA and SOD1are enthalpy driven exothermic process, mainly combined by electrostatic interaction.And the types of aggregations are different, Entropy values are different.(2) The CD spectra experiment shows that different DNA interacte with SOD1mainly in two structures which are ssDNA and quadruplex DNA. and DNA is still the original structure in the formed aggregates, does not change. ANS fluorescence experiments shows that adding DNA exposed more hydrophobic residues of SOD1, growth is positively correlated with the concentration of DNA, add the DNA so that different degrees of hydrophobic residues of SOD1exposed disaggregated into two groups, Poly (dC)12、Poly (dG)12was greater than the Poly (dA)12、Poly (dT)12, the quadruplex [P1]、[P2]、[d (TG4T)]4was greater than the corresponding ss DNA. Characteristic peaks appear blue shift, indicating that the SOD1conformation further changes, hydrophobicity, degree of aggregation increases.(3) Right angle light scattering finds:the SOD1aggregation reaction is promoted rapid equilibrium by different types of DNA, and the formation of aggregates have significantly different particle size, two sets of columns, the size of SOD1add Poly(dC)12, Poly(dG)12was greater than aggregation of the corresponding Poly(dA)12, Poly (dT)12, the aggregation of SOD1add quadruplex [PI],[P2],[d (TG4T)]4was greater than the size of adding corresponding ss DNA, while the concentration increasing, the aggregate particle size increases.(4) inverted fluorescence microscopy and transmission electron microscopy show that, the fluorescence intensity which SOD1aggregates prompted by Poly(dA)12、 Poly(dT)12is weaker than the aggregates formed from Poly(dC)12、Poly(dG)12, and the former is mainly formed a small spherical amorphous body, the latter is mainly formed fibrous aggregates. The CR UV absorption experiments show that the quadruplex [P1]、[P2]、[d (TG4T)]4inducing the formation of SOD1aggregates of amyloid structure is more than ss DNA.(5) MTT Cytotoxicity experiment finds that the survival rate of the cells which adds Poly(dA)12、Poly(dT)12, ss [P1]、ss[P2]、ss [d(TG4T)]4forming small amorphous aggregates is lower than which adds Poly(dC)12、Poly(dG)12、quadruplex [P1]、[P2]、[d(TG4T)]4forming fibrous aggregates, so as to establish a presumed relationship between the aggregation type and the cytotoxicity.