Chothia C, Lesk A M
EMBO J. 1986 Apr;5(4):823-6. doi: 10.1002/j.1460-2075.1986.tb04288.x.
Homologous proteins have regions which retain the same general fold and regions where the folds differ. For pairs of distantly related proteins (residue identity approximately 20%), the regions with the same fold may comprise less than half of each molecule. The regions with the same general fold differ in structure by amounts that increase as the amino acid sequences diverge. The root mean square deviation in the positions of the main chain atoms, delta, is related to the fraction of mutated residues, H, by the expression: delta(A) = 0.40 e1.87H.
同源蛋白质具有保持相同总体折叠的区域和折叠不同的区域。对于远缘相关蛋白质对（残基同一性约为20%），具有相同折叠的区域可能占每个分子的不到一半。具有相同总体折叠的区域在结构上的差异随着氨基酸序列的分歧而增加。主链原子位置的均方根偏差δ与突变残基的分数H通过以下表达式相关：δ(A)=0.40 e1.87H 。
