The γ Turn. Evidence for a New Folded Conformation in Proteins
The γ Turn. Evidence for a New Folded Conformation in Proteins
复制标题
蛋白质中新折叠构象的证据。
DOI：
10.1021/ma60030a031
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发表时间：
1972
期刊：
影响因子：
5.5
通讯作者：
B. Matthews
中科院分区：
文献类型：
--
作者：
B. Matthews
Oi) and/or (N3—H3-•·· Oi), which were originally considered too short to be al-lowed. 12· 13 There is precedent for the occurrence of this conformation in globular proteins. For example, in lyso-zyme, 18 Phe (38) has been reported to have the conformation (112J,—27), and in ribonuclease S19 Lys (37) was reported to have a conformation near (77,—45). On the other hand, participation of a residue with this conformation in a 7 turn has not been heretofore reported. It will be noted in Table I that the biggest discrepancy between the observed conforma-tions20 and those predicted by Némethy and Printz6 is (—40,+ 36) for (,). Since these differences are approximately equal and opposite, they tendto offset each other in such a way that the observed course of the polypeptide chain is quite similar to that predicted theoretically (see Figure 1 of ref 6). The predicted values for (7, 7) lie just outside the low-energy region of most conformational maps, whereas the observed value for Ser (25) lies inside the “fully allowed” re-gion. 12 It may be noted that model-building experiments show that another polypeptide chain reversal is possible by utilizing three-carbon atoms, Ci “, C2 “, C3 “, with dihedral angles approximately (70,—170),(—86, 57), and (—155,—60). In this case the hydrogen bonds are (Ns—H3··· Oi), as in the7 turn, and (N4—4·· O0)[c/. N1H1··-03], the former arising from conformational angles inverse to those at C2 “in the 7 turn. This alternative three-a-carbon chain re-versal might therefore be designated the “inverse 7 turn,” or the
