Unique
residue pairs matching the PDB (2b4z) crystal structure of cytochrome C. (a)
Known residues, helix, and loop regions triggering alkaline and acidic
conformational changes in cytochrome C (red, acidic transition; blue,
alkaline transition; black, heme group). (b) Residue pairs having
maximum abundance at pH ≤ 5, corresponding to the acidic form
of cytochrome C (red, links below the distance limit of 25 Å;
blue, links longer than 25 Å). (c) Residue pairs having maximum
abundance at pH 6–7, corresponding to the neutral form (red,
links below the distance limit of 25 Å; blue, links longer than
25 Å). (d) Residue pairs having maximum abundance at pH ≥
8, corresponding to the alkaline form (red, links below the distance
limit of 25 Å; blue, links longer than 25 Å).