Smith G D, Zabrocki J, Flak T A, Marshall G R
Medical Foundation of Buffalo, Inc. NY.
Int J Pept Protein Res. 1991 Mar;37(3):191-7. doi: 10.1111/j.1399-3011.1991.tb00270.x.
The structure of Z-Pro psi [CN4]-Ala-OBzl has been determined by X-ray crystallographic techniques. The structure crystallizes in space group P2(1) with cell constants a = 22.176(3) A, b = 6.141(1)A, c = 8.275(1) A, beta = 98.31(1), and Z = 2. The structure has been refined to a residual of 0.038 for 2538 independent data. The amide bond between the prolyl and alanyl residues is cis, a result of the presence of the tetrazole ring system, as is the urethane bond linking the benzyloxycarbonyl and the prolyl groups. A comparison of the structures in this study to other structures containing cis amide bonds shows that the tetrazole ring system, when incorporated into peptides, mimics a cis amide bond. Changes in the distance between the alpha-carbons adjacent to the tetrazole rings in the linear peptide as compared with the bicyclic diketopiperazine required a reassessment of the conformational mimicry with the cis amide bond.
Z-脯氨酰ψ[CN4]-丙氨酰-苄酯的结构已通过X射线晶体学技术确定。该结构在空间群P2(1)中结晶，晶胞参数为a = 22.176(3) Å，b = 6.141(1) Å，c = 8.275(1) Å，β = 98.31(1)，Z = 2。该结构已针对2538个独立数据精修至残余因子为0.038。脯氨酰和丙氨酰残基之间的酰胺键为顺式，这是四唑环系统存在的结果，连接苄氧羰基和脯氨酰基团的氨基甲酸酯键也是如此。本研究中该结构与其他含有顺式酰胺键的结构的比较表明，四唑环系统在掺入肽中时模拟了顺式酰胺键。与双环二酮哌嗪相比，线性肽中与四唑环相邻的α-碳原子之间距离的变化需要重新评估与顺式酰胺键的构象模拟。
