Molecular Environmental Effects on the Puckering of the Proline Ring
The conformational properties of polyproline and peptides containing proline have been studied extensively by semi-empirical [1–15] and molecular orbital energy calculations. [16, 17] The importance of the flexibility of the pyrrolidine ring has been realized relatively recently and the ring flexibility has been considered in some of the calculations [4, 5, 7–9, 12–16]. Apart from the well-known X-ray analysis of crystal structures, NMR has emerged as a powerful tool in studying the puckering of the proline ring [18, 19]. The mobilities of the ring atoms have been inferred from relaxation time measurements [20–22]. In the light of these experimental studies, it is interesting to theoretically analyze the nature of the ring puckering. In this paper, we examine some aspects of the effect of molecular environment on the puckering of the prolyl ring.
KeywordsKcal Mole Torsion Angle Trans Conformation Global Energy Minimum Energy Plot
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