erwin chargaff contributed to the discovery of dna structure.
erwin chargaff contributed to the discovery of dna structure.
who contributed to the discovery of dna structure?
erwin chargaff
bullet::::- erwin chargaff disproves the "tetranucleoide theory" of dna structure and determines that the composition of double-stranded dna follows the rule, %a = %t and %g = %c (chargaff's rule). this discovery was critical to the formulation of the watson-crick model of dna structure.









































bullet::::- neil bartlett mixes xenon and platinum hexafluoride leading to the first synthesis of a noble gas compound, xenon hexafluoroplatinate (1962).
list of experiments
since the discovery and crystallization of z-dna in 1979, the configuration has left scientists puzzled about the pathway and mechanism from the b-dna configuration to the z-dna configuration. the conformational change from b-dna to the z-dna structure was unknown at the atomic level, but in 2010, computer simulations conducted by lee et. al. were able to computationally determine that the step-wise propagation of a b-to-z transition would provide a lower energy barrier than the previously hypothesized concerted mechanism. since this was computationally proven, the pathway would still need to be tested experimentally in the lab for further confirmation and validity, in which lee et. al. specifically states in their journal article, "the current [computational] result could be tested by single-molecule fret (smfret) experiments in the future." in 2018, the pathway from b-dna to z-dna was experimentally proven using smfret assays. this was performed by measuring the intensity values between the donor and acceptor fluorescent dyes, also known as fluorophores, in relation to each other as they exchange electrons, while tagged onto a dna molecule. the distances between the fluorophores could be used to quantitatively calculate the changes in proximity of the dyes and conformational changes in the dna. a z-dna high affinity binding protein, hzαadar1, was used at varying concentrations to induce the transformation from b-dna to z-dna. the smfret assays revealed a b* transition state, which formed as the binding of hzαadar1 accumulated on the b-dna structure and stabilized it. this step occurs to avoid high junction energy, in which the b-dna structure is allowed to undergo a conformational change to the z-dna structure without a major, disruptive change in energy. this result coincides with the computational results of lee et. al. proving the mechanism to be step-wise and its purpose being that it provides a lower energy barrier for the conformational change from the b-dna to z-dna configuration. contrary to the previous notion, the binding proteins do not actually stabilize the z-dna conformation after it is formed, but instead they actually promote the formation of the z-dna directly from the b* conformation, which is formed by the b-dna structure being bound by high affinity proteins.
z-dna