TY - JOUR
T1 - Conformational preferences of β- and γ-aminated proline analogues
AU - Flores-Ortega, Alejandra
AU - Casanovas, Jordi
AU - Nussinov, Ruth
AU - Alemán, Carlos
PY - 2008/11/6
Y1 - 2008/11/6
N2 - Quantum mechanical calculations have been used to investigate how the incorporation of an amino group to the Cβ- or C γ-positions of the pyrrolidine ring affects the intrinsic conformational properties of the proline. Specifically, a conformational study of the N-acetyl-N′-memylamide derivatives of four isomers of aminoproline, which differ not only in the β- or γ-position of the substituent but also in its cis or trans relative disposition, has been performed. To further understand die role of the intramolecular hydrogen bonds between the backbone carbonyl groups and the amino side group, a conformational study was also performed on die corresponding four analogues of (dimethylamino)proline. In addition, the effects of solvation on aminoproline and (dimethylamino)proline dipeptides have been evaluated using a self-consistent reaction field model, and considering four different solvents (carbon tetrachloride, chloroform, methanol and water). Results indicate that the incorporation of the amino substituent into the pyrrolidine ring affects the conformational properties, with backbone⋯side chain intramolecular hydrogen bonds detected when it is incorporated in a cis relative disposition. In general, the incorporation of the amino side group tends to stabilize those structures where the peptide bond involving the pyrrolidine nitrogen is arranged in cis. The aminoproline isomer with the substituent attached to the Cγ-pposition with a cis relative disposition is the most stable in the gas phase and in chloroform, methanol and water solutions. Replacement of the amino side group by the dimethylamino substituent produces significant changes in the potential energy surfaces of the four investigated (dimethylarnino)proline-containing dipeptides. Thus, these changes affect not only the number of minima, which increases considerably, but also the backbone and pseudorotational preferences. In spite of these effects, comparison of the conformational preferences, i.e., the more favored conformera, calculated for different isomers of aminoproline and (dimethylamino)proline dipeptides showed a high degree of consistency for the two families of compounds.
AB - Quantum mechanical calculations have been used to investigate how the incorporation of an amino group to the Cβ- or C γ-positions of the pyrrolidine ring affects the intrinsic conformational properties of the proline. Specifically, a conformational study of the N-acetyl-N′-memylamide derivatives of four isomers of aminoproline, which differ not only in the β- or γ-position of the substituent but also in its cis or trans relative disposition, has been performed. To further understand die role of the intramolecular hydrogen bonds between the backbone carbonyl groups and the amino side group, a conformational study was also performed on die corresponding four analogues of (dimethylamino)proline. In addition, the effects of solvation on aminoproline and (dimethylamino)proline dipeptides have been evaluated using a self-consistent reaction field model, and considering four different solvents (carbon tetrachloride, chloroform, methanol and water). Results indicate that the incorporation of the amino substituent into the pyrrolidine ring affects the conformational properties, with backbone⋯side chain intramolecular hydrogen bonds detected when it is incorporated in a cis relative disposition. In general, the incorporation of the amino side group tends to stabilize those structures where the peptide bond involving the pyrrolidine nitrogen is arranged in cis. The aminoproline isomer with the substituent attached to the Cγ-pposition with a cis relative disposition is the most stable in the gas phase and in chloroform, methanol and water solutions. Replacement of the amino side group by the dimethylamino substituent produces significant changes in the potential energy surfaces of the four investigated (dimethylarnino)proline-containing dipeptides. Thus, these changes affect not only the number of minima, which increases considerably, but also the backbone and pseudorotational preferences. In spite of these effects, comparison of the conformational preferences, i.e., the more favored conformera, calculated for different isomers of aminoproline and (dimethylamino)proline dipeptides showed a high degree of consistency for the two families of compounds.
UR - http://www.scopus.com/inward/record.url?scp=84961974204&partnerID=8YFLogxK
U2 - 10.1021/jp807638p
DO - 10.1021/jp807638p
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C2 - 18842022
AN - SCOPUS:84961974204
VL - 112
SP - 14045
EP - 14055
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 44
ER -