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Casanovas J, Revilla-López G, Crisma M, Toniolo C, Alemán C. Factors Governing the Conformational Tendencies of Cα-Ethylated α-Amino Acids: Chirality and Side-Chain Size Effects. J Phys Chem B 2012; 116:13297-307. [DOI: 10.1021/jp3045115] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jordi Casanovas
- Departament
de Química, Escola Politècnica Superior, Universitat de Lleida, 25001 Lleida, Spain
| | - Guillermo Revilla-López
- Departament d’Enginyeria Química,
E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, 08028
Barcelona, Spain
| | - Marco Crisma
- ICB, Padova
Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy
| | - Claudio Toniolo
- ICB, Padova
Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy
| | - Carlos Alemán
- Departament d’Enginyeria Química,
E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, 08028
Barcelona, Spain
- Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, 08028 Barcelona, Spain
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2
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Malek K, Makowski M, Królikowska A, Bukowska J. Comparative studies on IR, Raman, and surface enhanced Raman scattering spectroscopy of dipeptides containing ΔAla and ΔPhe. J Phys Chem B 2012; 116:1414-25. [PMID: 22208201 DOI: 10.1021/jp208586j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three dipeptides containing dehydroresidues (ΔAla, Δ((Z))Phe, and Δ((E))Phe) were examined by IR, Raman, and surface-enhanced Raman techniques for the first time. The effect of the size and isomer type of the β-substituent in the dehydroresidue on the conformational structure of the peptide was evaluated by using the analysis of IR and Raman bands. Additionally, SERS spectroscopy provided insight into the adsorption mechanism of these species on the metal surface. SERS spectra were recorded at alkaline pH on the silver sol using visible light excitation. The dehydroresidues studied here strongly influenced the SERS profile of the peptides. The most pronounced SERS signal for all dipeptides was assigned to the symmetric stretching vibration of the carboxylate ions. This indicates that the dehydropeptides studied here primarily adsorb via the deprotonated carboxylic group. Additionally, the enhanced SERS bands in the range 1550-1650 cm(-1) show differences in contribution of the dehydroresidue to the adsorption mechanism of the studied peptides.
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Affiliation(s)
- Kamilla Malek
- Faculty of Chemistry, Jagiellonian Chemistry, Ingardena 3, 30-060 Krakow, Poland.
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3
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Chen T, Qin Z, Qi Y, Deng T, Ge X, Wang J, Hou X. Degradable polymers from ring-opening polymerization of α-angelica lactone, a five-membered unsaturated lactone. Polym Chem 2011. [DOI: 10.1039/c1py00067e] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A degradable polymer was prepared from α-angelica lactone, a five-membered unsaturated lactone, by ring-opening polymerization.
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Affiliation(s)
- Tieniu Chen
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
| | - Zhangfeng Qin
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
| | - Yongqin Qi
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
| | - Tiansheng Deng
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
| | - Xiaojing Ge
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
| | - Jianguo Wang
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
| | - Xianglin Hou
- State Key Laboratory of Coal Conversion
- Institute of Coal Chemistry
- Chinese Academy of Sciences
- Taiyuan
- PR China
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4
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ALEMÁN CARLOS. Effect of the environment and role of the π-π stacking interactions in the stabilization of the 310-helix conformation in dehydroalanine oligopeptides. ACTA ACUST UNITED AC 2009. [DOI: 10.1111/j.1399-3011.1995.tb01075.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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5
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Torras J, Zanuy D, Crisma M, Toniolo C, Betran O, Alemán C. Correlation between symmetry breaker position and the preferences of conformationally constrained homopeptides: A molecular dynamics investigation. Biopolymers 2008; 90:695-706. [DOI: 10.1002/bip.21031] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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6
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Casanovas J, Nussinov R, Alemán C. Intrinsic conformational preferences of C(alpha,alpha)-dibenzylglycine. J Org Chem 2008; 73:4205-11. [PMID: 18465898 DOI: 10.1021/jo8005528] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The intrinsic conformational preferences of C (alpha,alpha)-dibenzylglycine, a symmetric alpha,alpha-dialkylated amino acid bearing two benzyl substituents on the alpha-carbon atom, have been determined using quantum chemical calculations at the B3LYP/6-31+G(d,p) level. A total of 46 minimum energy conformations were found for the N-acetyl- N'-methylamide derivative, even though only nine of them showed a relative energy lower than 5.0 kcal/mol. The latter involves C 7, C 5, and alpha' backbone conformations stabilized by intramolecular hydrogen bonds and/or N-H...pi interactions. Calculation of the conformational free energies in different environments (gas-phase, carbon tetrachloride, chloroform, methanol, and water solutions) indicates that four different minima (two C 5 and two C 7) are energetically accessible at room temperature in the gas phase, while in methanol and aqueous solutions one such minimum (C 5) becomes the only significant conformation. Comparison with results recently reported for C (alpha,alpha)-diphenylglycine indicates that substitution of phenyl side groups by benzyl enhances the conformational flexibility leading to (i) a reduction of the strain of the peptide backbone and (ii) alleviating the repulsive interactions between the pi electron density of the phenyl groups and the lone pairs of the carbonyl oxygen atoms.
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Affiliation(s)
- Jordi Casanovas
- Departament de Química, Escola Politècnica Superior, Universitat de Lleida, c/Jaume II no. 69, Lleida, Spain.
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Flores-Ortega A, Jiménez AI, Cativiela C, Nussinov R, Alemán C, Casanovas J. Conformational preferences of alpha-substituted proline analogues. J Org Chem 2008; 73:3418-27. [PMID: 18351745 PMCID: PMC2679371 DOI: 10.1021/jo702710x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DFT calculations at the B3LYP/6-31+G(d,p) level have been used to investigate how the replacement of the alpha hydrogen by a more sterically demanding group affects the conformational preferences of proline. Specifically, the N-acetyl-N'-methylamide derivatives of L-proline, L-alpha-methylproline, and L-alpha-phenylproline have been calculated, with both the cis/trans isomerism of the peptide bonds and the puckering of the pyrrolidine ring being considered. The effects of solvation have been evaluated by using a Self-Consistent Reaction Field model. As expected, tetrasubstitution at the alpha carbon destabilizes the conformers with one or more peptide bonds arranged in cis. The lowest energy minimum has been found to be identical for the three compounds investigated, but important differences are observed regarding other energetically accessible backbone conformations. The results obtained provide evidence that the distinct steric requirements of the substituent at C (alpha) may play a significant role in modulating the conformational preferences of proline.
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Affiliation(s)
- Alejandra Flores-Ortega
- Departament d’Enginyeria Química, E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Avda. Diagonal n° 647, 08028 Barcelona, Spain
| | - Ana I. Jiménez
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza – CSIC, 50009 Zaragoza, Spain
| | - Carlos Cativiela
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza – CSIC, 50009 Zaragoza, Spain
| | - Ruth Nussinov
- Basic Research Program, SAIC-Frederick, Inc. Center for Cancer Research Nanobiology Program, NCI, Frederick, MD 21702, USA
- Department of Human Genetics Sackler, Medical School, Tel Aviv University, Tel Aviv 69978, Israel
| | - Carlos Alemán
- Departament d’Enginyeria Química, E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Avda. Diagonal n° 647, 08028 Barcelona, Spain
| | - Jordi Casanovas
- Departament de Química, Escola Politècnica Superior, Universitat de Lleida, c/Jaume II n° 69, 25001 Lleida, Spain
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8
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Houk KN, Jabbari A, Hall HK, Alemán C. Why δ-Valerolactone Polymerizes and γ-Butyrolactone Does Not. J Org Chem 2008; 73:2674-8. [DOI: 10.1021/jo702567v] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- K. N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024-1569, Department of Chemistry, The University of Arizona, Tucson, Arizona, 85721, and Department d'Enginyeria Química, E.T.S. de'Enginyera Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 547 Barcelona E-08028 Spain
| | - Arash Jabbari
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024-1569, Department of Chemistry, The University of Arizona, Tucson, Arizona, 85721, and Department d'Enginyeria Química, E.T.S. de'Enginyera Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 547 Barcelona E-08028 Spain
| | - H. K. Hall
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024-1569, Department of Chemistry, The University of Arizona, Tucson, Arizona, 85721, and Department d'Enginyeria Química, E.T.S. de'Enginyera Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 547 Barcelona E-08028 Spain
| | - Carlos Alemán
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90024-1569, Department of Chemistry, The University of Arizona, Tucson, Arizona, 85721, and Department d'Enginyeria Química, E.T.S. de'Enginyera Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 547 Barcelona E-08028 Spain
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Casanovas J, Jiménez AI, Cativiela C, Nussinov R, Alemán C. 1-amino-2-phenylcyclopentane-1-carboxylic acid: a conformationally restricted phenylalanine analogue. J Org Chem 2007; 73:644-51. [PMID: 18081347 DOI: 10.1021/jo702107s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
DFT calculations at the B3LYP/6-311G(d,p) level have been used to investigate the intrinsic conformational preferences of 1-amino-2-phenylcyclopentane-1-carboxylic acid (c5Phe), a constrained analogue of phenylalanine in which the alpha and beta carbons are included in a cyclopentane ring. Specifically, the N-acetyl-N'-methylamide derivatives of the cis and trans stereoisomers, where cis and trans refer to the relative position between the amino group and the phenyl ring, have been calculated. Solvent effects have been examined using a self-consistent reaction field (SCRF) method. Results indicate that the conformational space of the cis stereoisomer is much more restricted than that of the trans derivative both in the gas phase and in solution.
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Affiliation(s)
- Jordi Casanovas
- Departament de Química, Escola Politècnica Superior, Universitat de Lleida, c/Jaume II No. 69, Lleida E-25001, Spain.
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10
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Ellis TK, Ueki H, Yamada T, Ohfune Y, Soloshonok VA. Design, synthesis, and evaluation of a new generation of modular nucleophilic glycine equivalents for the efficient synthesis of sterically constrained alpha-amino acids. J Org Chem 2007; 71:8572-8. [PMID: 17064036 DOI: 10.1021/jo0616198] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new generation of modular achiral glycine equivalents have been evaluated with respect to their synthetic utility for the production of tailor-made, sterically constrained alpha-amino acids, which proved to be the most efficient approach developed to date for the synthesis of symmetrical alpha,alpha-disubstituted-alpha-amino acids. Among the new series of achiral glycine equivalents, one was found to be a superior glycine derivative for the Michael additions with various (R)- or (S)-N-(E-enoyl)-4-phenyl-1,3-oxazolidin-2-ones representing a general and practical synthesis of sterically constrained beta-substituted pyroglutamic acids. In particular, the application of these complexes allowed for the preparation of several beta-substituted pyroglutamic acids which include electron-releasing and sterically demanding substituents in the structure thus increasing the synthetic efficiency and expanding the generality of these Michael addition reactions.
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Affiliation(s)
- Trevor K Ellis
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, USA
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11
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12
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Ellis TK, Martin CH, Ueki H, Soloshonok VA. Efficient, practical synthesis of symmetrically α,α-disubstituted α-amino acids. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(02)02719-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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13
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Alemán C, Jiménez AI, Cativiela C, Perez JJ, Casanovas J. Influence of the Phenyl Side Chain on the Conformation of Cyclopropane Analogues of Phenylalanine. J Phys Chem B 2002. [DOI: 10.1021/jp026381f] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Carlos Alemán
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain, Departamento de Química Orgánica, ICMA, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Departament de Química, Escola Universitària Politècnica, Universitat de Lleida, c/Jaume II n° 69, 25001 Lleida, Spain
| | - Ana I. Jiménez
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain, Departamento de Química Orgánica, ICMA, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Departament de Química, Escola Universitària Politècnica, Universitat de Lleida, c/Jaume II n° 69, 25001 Lleida, Spain
| | - Carlos Cativiela
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain, Departamento de Química Orgánica, ICMA, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Departament de Química, Escola Universitària Politècnica, Universitat de Lleida, c/Jaume II n° 69, 25001 Lleida, Spain
| | - Juan J. Perez
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain, Departamento de Química Orgánica, ICMA, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Departament de Química, Escola Universitària Politècnica, Universitat de Lleida, c/Jaume II n° 69, 25001 Lleida, Spain
| | - Jordi Casanovas
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain, Departamento de Química Orgánica, ICMA, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Departament de Química, Escola Universitària Politècnica, Universitat de Lleida, c/Jaume II n° 69, 25001 Lleida, Spain
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14
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Elstner M, Jalkanen K, Knapp-Mohammady M, Frauenheim T, Suhai S. DFT studies on helix formation in N-acetyl-(L-alanyl)n-N′-methylamide for n=1–20. Chem Phys 2000. [DOI: 10.1016/s0301-0104(00)00100-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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17
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Alemán C, Puiggalí J. Preferences of the Oxalamide and Hydrazide Moieties in Vacuum and Aqueous Solution. A Comparison with the Amide Functionality. J Org Chem 1998. [DOI: 10.1021/jo980399y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Carlos Alemán
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
| | - Jordi Puiggalí
- Departament d'Enginyeria Química, E.T.S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
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18
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19
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Alemán C, Ishiki HM, Armelin EA, Abrahão Junior O, Galembeck SE. Free energies of solvation for peptides and polypeptides using SCRF methods. Chem Phys 1998. [DOI: 10.1016/s0301-0104(98)00134-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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20
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Alemán C. Chain conformation in polyretropeptides III: design of a 3(10) helix using alpha,alpha-dialkylated amino acids and retropeptide bonds. Proteins 1997; 29:575-82. [PMID: 9408953 DOI: 10.1002/(sici)1097-0134(199712)29:4<575::aid-prot16>3.0.co;2-j] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Computer simulations have been used to design a polypeptide with a 3(10) helix conformation. The study has been been performed taking advantage of the intrinsic helix forming tendency of alpha-Aminoisobutyric acid. In order to avoid the formation of the alpha helix, which is the other common helical conformation adopted by alpha-Aminoisobutyric acid-based peptides, retropeptide bonds have been included in the sequence. Thus, retropeptides are not able to form the intramolecular hydrogen bonding interactions characteristic of the alpha helix. The influences of both the peptide length and the solvent have been examined and compared with those of the polypeptide without retropeptide bonds.
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Affiliation(s)
- C Alemán
- Departament d'Enginyería Química, E.T.S. d'Enginyers Industrials de Barcelona, Universitat Politécnica de Catalunya, Spain
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Affiliation(s)
- Salvador León
- Departament d'Enginyeria Química, ETS d'Enginyers Industrials de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
| | - Carlos Alemán
- Departament d'Enginyeria Química, ETS d'Enginyers Industrials de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
| | - Sebastián Muñoz-Guerra
- Departament d'Enginyeria Química, ETS d'Enginyers Industrials de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
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22
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Alemán C. Conformational Properties of α-Amino Acids Disubstituted at the α-Carbon. J Phys Chem B 1997. [DOI: 10.1021/jp963339+] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Jain RM, Rajashankar KR, Ramakumar S, Chauhan VS. First Observation of Left-Handed Helical Conformation in a Dehydro Peptide Containing Two l-Val Residues. Crystal and Solution Structure of Boc-l-Val-ΔPhe-ΔPhe-ΔPhe-l-Val-OMe,. J Am Chem Soc 1997. [DOI: 10.1021/ja961460o] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- R. M. Jain
- Contribution from the International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India, and Department of Physics, Indian Institute of Science, Bangalore-560012, India
| | - K. R. Rajashankar
- Contribution from the International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India, and Department of Physics, Indian Institute of Science, Bangalore-560012, India
| | - S. Ramakumar
- Contribution from the International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India, and Department of Physics, Indian Institute of Science, Bangalore-560012, India
| | - V. S. Chauhan
- Contribution from the International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi-110067, India, and Department of Physics, Indian Institute of Science, Bangalore-560012, India
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Affiliation(s)
- Gustavo A. Arteca
- Département de Chimie et Biochimie, Laurentian University, Ramsey Lake Road, Sudbury, Ontario, Canada P3E 2C6
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Orozco M, Roca R, Alemán C, Busquets M, López J, Luque F. Theoretical representation of solvent effects in the study of biochemical systems. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0166-1280(96)04529-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Navas JJ, Alemán C, Muñoz-Guerra S. Effects of Aqueous and Organic Solvents on the Conformational Properties of the Helix-Forming alpha-Methyl-beta-L-aspartamyl Residue. J Org Chem 1996; 61:6849-6855. [PMID: 11667579 DOI: 10.1021/jo952179f] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational preferences of N-acetyl-N'-methyl-alpha-methyl-beta-L-aspartamide, which is the model compound for helical poly(beta-L-aspartate)s, have been determined by ab initio SCF-MO computations. Two driving patterns have been found for the existing 13 minimum energy conformations: (i) intramolecular hydrogen bonding interactions of both amide-amide and amide-ester type; and (ii) repulsive interactions between the four oxygen atoms contained in the molecule. Self-consistent reaction-field (SCRF) calculations based on the method proposed by Miertus, Scrocco, and Tomasi have been performed in order to evaluate the effect of the solvent on the conformational preferences of the compound subject of study. Water and carbon tetrachloride were the solvents chosen for this purpose, and results have been discussed and interpreted on the basis of their electronic structures. The conclusions drawn from this study are of assistance to understand some features of the conformational transitions experimentally found in poly(beta-L-aspartate)s.
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Affiliation(s)
- Juan José Navas
- Departament d'Enginyería Química, E. T. S. d'Enginyers Industrials, Universitat Politècnica de Catalunya, Diagonal 647, Barcelona E-08028, Spain
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Abstract
The potential energy surface of the phi [NHCO] delta Ala dipeptide has been computed using ab initio quantum mechanical calculations at different theoretical levels. Three degenerate minima were found and characterized. The most favoured conformation is stabilized by an intramolecular hydrogen bonding interaction. The other two minima correspond to helical and malonamide-like conformations, being 4.6 kcal/mol and 6.9 kcal/mol less stable than the lowest energy conformation, respectively. Influence of solvent effects on the relative stabilities of the different conformations have been accounted using SCRF calculations. Two implicit solvent models have been considered: water and CCl4. The results indicate that in the both cases the conformation with an intramolecular hydrogen bonding interaction retains its lowest energy.
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Affiliation(s)
- C Alemán
- Department d'Enginyeria Química, E.T.S.I.I.B., Universitat Politècnica de Catalunya, Barcelona, Spain
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Navarro E, Alemán C, Subirana JA, Puiggalí J. On the Crystal Structure of Nylon 55. Macromolecules 1996. [DOI: 10.1021/ma960005+] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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