The transcription factor AP-1 is a heterodimer consisting of c-jun and c-fos. C-jun and c-fos are soluble proteins that can be localized to either the cytosol or nucleus of a cell. C-jun and c-fos dimerize through a leucine zipper motif. In a leucine zipper motif, every 7 amino acid residues, or 2 full turns of an alpha helix, are leucine resides. Leucine and other amino acids on one face of the helix come together to form an opposite alpha helix that has a similar arrangement of leucine and other amino acids. Which solvent would be LEAST favorable for c-fos/c-jun dimerization?

Generally, leucine is hydrophobic in nature and it has a carbon-hydrogen side chain. Therefore, it is not advisable to use an hydrophobic solvent because the leucine zipper would interact with both the opposite alpha helix and the solvent. This will ultimately hinder the dimer creation. Thus, the best solvent which is the least polar in the list is hexane.

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