Amino acid mutation correlation relationships of 4 couple position pairs.

<p>The 4 position pairs have high mutation correlation coefficients (R₇₁₋₂₅ = 0.8388, R₄₆₋₁₄ = 0.8522, R₈₃₋₁₄ = 0.892, and R₆₁₋₅₆ = 0.9742), and the position mutation factors (<i>t_k,l</i>) of 20 amino acid types at the couple position pairs show higher correlation relationship.