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GENE CONTROL. “Extensive studies have been carried out which have shown that methylation of DNA is generally associated with turning off transcription; conversely, demethylation is associated with the initiation of transcription or the expression of the gene.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

DNA METHYLATION. “One of the principal modifications of the nucleic acids, especially in higher eukaryotes, is methylation of cytosine on the 5 position where the cytosine is followed by a guanine.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

STABILIZERS. “The major conclusion reached from these studies is that the equilibrium between the B form and Z form of poly(dG-dC) is strongly influenced by cations and by the substituents which are attached to the polymer. A number of these substituents profoundly influence the equilibrium between the two forms and favor the Z-DNA conformation.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

THE STABILITY EXPLANTATION. “Since purine nucleotides can adopt the syn conformation more readily than pyrimidine nucleotides, it is reasonable to believe that the Z conformation will be favored in sequences with alternating purines and pyrimidines.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

ORIENTATION SWITCH. “One consequence of these differences in conformation is that the bases in Z-DNA have a different orientation relative to the sugar phosphate backbone than they do in B-DNA. In essence, the bases must "flip over" in order to go from one form to the other.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

SURPRISE FINDING. “It has been shown that Z-DNA can exist in the same molecule with B-DNA. This was shown by cloning oligo(dG-dC) into plasmids and then isolating segments containing both the plasmid DNA and the oligo(dG-dC).” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn

THE FACTORS. “Because of increased phosphate-phosphate repulsion forces the left-handed helical structure is inherently less stable than B-DNA in a physiological salt solution. In view of the equilibrium between the two forms, it is clear that a number of components in the environment could stabilize Z-DNA.” https://link.springer.com/content/pdf/10.1007/978-94-009-7052-6.pdf View in LinkedIn