Table 4 Key residues covered by APCs and their roles in co-occurrence cluster 2 of cytochrome c

Cys(C) 14 enhances axial ligand strength between His18 and the heme.

[32, 33]

Cys(C) 17 enhances axial ligand strength between His18 and the heme.

[32, 33]

His(H)18 forms an axial ligand with the heme from the proximal front.

[34, 35]

Tyr(Y)67, its hydroxyl group, forms a H-bond with side chains of Met80 for structural stabilization.

[36, 28]

Pro(P)71 helps coordinate the axial ligand between Met80 and the heme.

[37]

Pro(P)76 helps coordinate the axial ligand between Met80 and the heme.

[38]

Met(M)80 forms an axial ligand with the heme from the distal side.

[34, 35]

Phe(F)82 helps stabilize the native heme environment.

[39]

Gly(G)41 helps stabilize the axial ligand between Met80 and the heme.

[40]

Asn(N)52 maintains a hydrogen bond with the heme to stabilize the environment.

[41, 42]

One of Leu(L)94 or Tyr(Y)97 is required to provide a hydrophobic environment for the function of cyt-c.

[43]

One of Leu(L)94 or Tyr(Y)97 is required to provide a hydrophobic environment for the function of cyt-c.

[43]