In this study, 1064 nonhomologous "unsplit", "one-strand split" and "two-strand split" right-handed βαβ-units having standard α-helices and loops up to seven residues in length have been analyzed. It was found that the α-helices in these kinds of βαβ-units have different distributions of the hydrophobic and hydrophilic amino acid residues along the chain. In the unsplit βαβ-units, most α-helices have hydrophobic residues in positions N4-N7-N8-N11 or N6-N7-N10, where N1 is the first N-terminal residue. In the one-strand split βαβ-units, most α-helices have hydrophobic residues in positions N4-N7-N8-N11 and those in two-strand split βαβ-units in positions N4-N5-N8-N12. On the other hand, in all kinds of βαβ-units, there are commonly occurring hydrophobic stripes of type C4-C7-C8 at the C-terminal parts of the α-helices. As a rule, the C- and N-terminal hydrophobic stripes overlap and the extent of their overlapping determine the length of α-helices.

中文翻译：

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分裂和未分裂的βαβ单位的结构特征。

在这项研究中，分析了1064个非同源的“未分裂”，“单链分裂”和“两链分裂”右旋βαβ-单元，这些单元具有标准的α螺旋，并且环的长度最多为7个残基。发现这些β-β-单元中的α-螺旋在链上具有疏水性和亲水性氨基酸残基的不同分布。在未分裂的βαβ单元中，大多数α螺旋在N4-N7-N8-N11或N6-N7-N10位置具有疏水残基，其中N1是第一个N末端残基。在单链分裂的βαβ单元中，大多数α-螺旋在N4-N7-N8-N11位具有疏水残基，而在两链分裂的βαβ单元中在N4-N5-N8-N12位具有疏水残基。另一方面，在所有种类的βαβ单元中，在α螺旋的C末端部分通常存在C4-C7-C8型疏水条。