Mazaleyrat Jean-Paul, Wright Karen, Gaucher Anne, Toulemonde Nathalie, Dutot Laurence, Wakselman Michel, Broxterman Quirinus B, Kaptein Bernard, Oancea Simona, Peggion Cristina, Crisma Marco, Formaggio Fernando, Toniolo Claudio
SIRCOB, UMR CNRS 8086, University of Versailles, 78035 Versailles, France.
Chemistry. 2005 Nov 18;11(23):6921-9. doi: 10.1002/chem.200500187.
An induced axial chirality in the biphenyl core of the 2',1':1,2;1'',2'':3,4-dibenzcyclohepta-1,3-diene-6-amino-6-carboxylic acid (Bip) residue, a conformationally labile, atropoisomeric, C(alpha)-tetrasubstituted alpha-amino acid, was observed by CD and (1)H NMR spectroscopic techniques in the linear dipeptides Boc-Bip-Xaa*-OMe where Boc=tert-butoxycarbonyl, OMe=methoxy, and Xaa*=D- and/or L-Ala, -Val, -Leu, -Phe, -(alphaMe)Val and -(alphaMe)Leu. Chiral induction was significantly lower in the isomeric dipeptides Boc-Xaa*-Bip-OMe, with the Xaa* residue located at the N-terminus of Bip, as well as in the cyclic dipeptide cyclo-[Bip-L-Ala]. The results obtained in solution were confirmed by X-ray diffraction analysis of a crystalline sample of Boc-(R)-Bip-D-Ala-OMe.
通过圆二色光谱（CD）和核磁共振氢谱（¹H NMR）技术，在直链二肽Boc-Bip-Xaa*-OMe中观察到2',1':1,2;1'',2'':3,4-二苯并环庚-1,3-二烯-6-氨基-6-羧酸（Bip）残基的联苯核心中诱导产生的轴向手性，Bip是一种构象不稳定的、阻转异构的、α-碳四取代的α-氨基酸，其中Boc =叔丁氧羰基，OMe =甲氧基，且Xaa* = D-和/或L-丙氨酸、缬氨酸、亮氨酸、苯丙氨酸、(αMe)缬氨酸和(αMe)亮氨酸。在异构体二肽Boc-Xaa*-Bip-OMe中，手性诱导显著降低，其中Xaa*残基位于Bip的N端，在环二肽环-[Bip-L-丙氨酸]中也是如此。溶液中得到的结果通过Boc-(R)-Bip-D-丙氨酸-OMe晶体样品的X射线衍射分析得到证实。
