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Macdonald B, McCarley S, Noeen S, van Giessen AE. β-Hairpin Crowding Agents Affect α-Helix Stability in Crowded Environments. J Phys Chem B 2016; 120:650-9. [DOI: 10.1021/acs.jpcb.5b10575] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Bryanne Macdonald
- Department of Chemistry, Mount Holyoke College, South Hadley, Massachusetts 01075, United States
| | - Shannon McCarley
- Department of Chemistry, Mount Holyoke College, South Hadley, Massachusetts 01075, United States
| | - Sundus Noeen
- Department of Chemistry, Mount Holyoke College, South Hadley, Massachusetts 01075, United States
| | - Alan E. van Giessen
- Department of Chemistry, Mount Holyoke College, South Hadley, Massachusetts 01075, United States
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2
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Nymeyer H. How Efficient Is Replica Exchange Molecular Dynamics? An Analytic Approach. J Chem Theory Comput 2015; 4:626-36. [PMID: 26620937 DOI: 10.1021/ct7003337] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Replica exchange molecular dynamics (REMD) has become a standard technique for accelerating relaxation in biosimulations. Despite its widespread use, questions remain about its efficiency compared with conventional, constant temperature molecular dynamics (MD). An analytic approach is taken to describe the relative efficiency of REMD with respect to MD. This is applied to several simple two-state models and to several real proteins-protein L and the B domain of protein A-to predict the relative efficiency of REMD with respect to MD in actual applications. In agreement with others, we find the following: as long as there is a positive activation energy for folding, REMD is more efficient than MD; the effectiveness of REMD is strongly dependent on the activation enthalpy; and the efficiency of REMD for actual proteins is a strong function of the maximum temperature. Choosing the maximum temperature too high can result in REMD becoming significantly less efficient than conventional MD. A good rule of thumb appears to be to choose the maximum temperature of the REMD simulation slightly above the temperature at which the enthalpy for folding vanishes. Additionally, we find that the number of replicas in REMD, while important for simulations shorter than one or two relaxation times, has a minimal effect on the asymptotic efficiency of the method.
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Affiliation(s)
- Hugh Nymeyer
- Department of Chemistry & Biochemistry, The School of Computational Science and The Institute for Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-4380
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3
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Conformational behavior of polyalanine peptides with and without protecting groups of varying chain lengths: population of PP-II structure! J Mol Model 2015; 21:123. [PMID: 25903302 DOI: 10.1007/s00894-015-2671-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/31/2015] [Indexed: 10/23/2022]
Abstract
Oculopharyngeal muscular dystrophy (OPMD), a polyalanine myopathy, occurs due to expansion of homo-polyalanine stretch in normal polyadenylating binding protein nuclear 1 (PABPN1) protein from Ala10 to Ala11-17. Therefore, the conformational behavior of polyalanine peptides with n = 10-17, with and without terminal protecting groups, have been investigated with different starting geometries in water by molecular dynamics simulation studies. Alanine peptides are shown to give rise to unordered structure irrespective of starting geometry and not more than two residues at a stretch have the same/similar set of φ, ψ values. However, the final structure with terminal protecting groups look like β-strand. Unprotected poly-Ala peptides adopt twisted β-hairpin/multi hairpin like structure with increasing chain length. The number of residues having φ, ψ values in collagen region is found to be less in peptides with unprotected termini as compared to peptides with protected termini of same chain length. The results have been supported by recent synchrotron radiation circular dichroism spectroscopy of polyproline II and unordered secondary structures. Opening of the helical structure in poly-Ala peptides with protecting groups has been shown to take place from C-terminal and in peptides without protecting groups opening of helix starts from both terminals. Further, opening of helix takes more time in poly-Ala peptides without terminal protecting groups. The deviations in amide bond planarity have been discussed and compared with available experimental and computational results.
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Involvement of non-polyalanine (polyA) residues in aggregation of polyA proteins: Clue for inhibition of aggregation. Comput Biol Chem 2014; 53PB:318-323. [PMID: 25462338 DOI: 10.1016/j.compbiolchem.2014.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 11/11/2014] [Accepted: 11/11/2014] [Indexed: 11/21/2022]
Abstract
Presence of polyalanine (polyA) stretches in some proteins is found to be associated with their aggregation, which causes disorders in various developmental processes. In this work, inherent propensities towards aggregation of some residues, which are not part of the polyA stretches, have been identified by using the primary sequences of seven polyA proteins with the help of Betascan, PASTA and Tango programs and explored unambiguously. This provides a basis for proposing molecular mechanism of this type of aggregation. Reported suppression of aggregation of polyA proteins by chaperones like HSP40 and HSP70 is substantiated through molecular docking. The hydrophobic residues of identified aggregating region are found to be interacting with hydrophobic surface of chaperones. This suggests a crucial clue for possible way to inhibit the aggregation of such proteins.
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6
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Church MS, Ferry CE, van Giessen AE. Thermodynamics of peptide dimer formation. J Chem Phys 2012; 136:245102. [DOI: 10.1063/1.4730169] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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7
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Carmichael SP, Shell MS. A New Multiscale Algorithm and Its Application to Coarse-Grained Peptide Models for Self-Assembly. J Phys Chem B 2012; 116:8383-93. [DOI: 10.1021/jp2114994] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Scott P. Carmichael
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California
| | - M. Scott Shell
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California
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8
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Wu J, Zhen X, Shen H, Li G, Ren P. Gay-Berne and electrostatic multipole based coarse-grain potential in implicit solvent. J Chem Phys 2012; 135:155104. [PMID: 22029338 DOI: 10.1063/1.3651626] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A general, transferable coarse-grain (CG) framework based on the Gay-Berne potential and electrostatic point multipole expansion is presented for polypeptide simulations. The solvent effect is described by the Generalized Kirkwood theory. The CG model is calibrated using the results of all-atom simulations of model compounds in solution. Instead of matching the overall effective forces produced by atomic models, the fundamental intermolecular forces such as electrostatic, repulsion-dispersion, and solvation are represented explicitly at a CG level. We demonstrate that the CG alanine dipeptide model is able to reproduce quantitatively the conformational energy of all-atom force fields in both gas and solution phases, including the electrostatic and solvation components. Replica exchange molecular dynamics and microsecond dynamic simulations of polyalanine of 5 and 12 residues reveal that the CG polyalanines fold into "alpha helix" and "beta sheet" structures. The 5-residue polyalanine displays a substantial increase in the "beta strand" fraction relative to the 12-residue polyalanine. The detailed conformational distribution is compared with those reported from recent all-atom simulations and experiments. The results suggest that the new coarse-graining approach presented in this study has the potential to offer both accuracy and efficiency for biomolecular modeling.
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Affiliation(s)
- Johnny Wu
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712-1062, USA
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9
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Linse P, Palenčár P, Bleha T. A New Two-State Polymer Folding Model and Its Application to α-Helical Polyalanine. J Phys Chem B 2011; 115:11448-54. [DOI: 10.1021/jp2019395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Per Linse
- Physical Chemistry, Department of Chemistry, Lund University, Box 124, SE-221 00 Lund, Sweden
| | - Peter Palenčár
- Polymer Institute, Slovak Academy of Science, 845 41 Bratislava, Slovakia
| | - Tomáš Bleha
- Polymer Institute, Slovak Academy of Science, 845 41 Bratislava, Slovakia
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Palenčár P, Bleha T. Molecular dynamics simulations of the folding of poly(alanine) peptides. J Mol Model 2011; 17:2367-74. [PMID: 21360173 DOI: 10.1007/s00894-011-0997-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 01/26/2011] [Indexed: 11/29/2022]
Abstract
The secondary structures and the shapes of long-chain polyalanine (PA) molecules were investigated by all-atom molecular dynamics simulations using a modified Amber force field. Homopolymers of polyaminoacids such as PA are convenient models to study the mechanism of protein folding. It was found that the conformational structures of PA peptides are highly sensitive to the chain length. In the absence of solvent, straight α-helices dominate in short (n ∼ 20) peptides at room temperature. A shape transition occurs at a chain length n of 40-45; the compact helix-turn-helix structure (the double-leg hairpin) becomes favored over a straight α-helix. For n=60, double-leg and the triple-leg hairpins are the only structures present in PA molecules. An exploration of a chain organization in a cubic cavity revealed a clear predisposition of PA molecules for additional breaks in α-helices and the formation of multifolded hairpins. Furthermore, under confinement the hairpin structure becomes much looser, the antiparallel positions of helical stems are disturbed, and a sizeable proportion of the helical stems are transformed from α-helices into 3(10)-helices.
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Affiliation(s)
- Peter Palenčár
- Polymer Institute, Slovak Academy of Sciences, Dubravska cesta 9, 845 41, Bratislava, Slovakia
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Gee J, Shell MS. Two-dimensional replica exchange approach for peptide–peptide interactions. J Chem Phys 2011; 134:064112. [DOI: 10.1063/1.3551576] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Mu Y, Gao YQ. Self-assembly of polypeptides into left-handedly twisted fibril-like structures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:041927. [PMID: 19905362 DOI: 10.1103/physreve.80.041927] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Indexed: 05/28/2023]
Abstract
In this paper, we investigated the spontaneous formation of aggregation structures of amyloid-forming peptide (GGVVIA) using a coarse-grained model and Monte Carlo simulations. The effects of concentration and temperature on the formation of different aggregation structures were studied. Three types of aggregation structures, single-layer beta sheet, amorphous beta-sheet aggregate, and fibril-like structures, were observed in our simulations. The fibril-like structures obtained in simulations have a common cross-beta spine structure in which beta sheets twist in a left-handed fashion. The averaged twisting angle of the beta sheet in the fibril-like structures is 12 degrees +/-2 degrees. Moreover, it was found that the peptides in the same beta sheets prefer to arrange in a parallel way, which is consistent with the corresponding GGVVIA crystalline structure. On the other hand, it was found that there is a rich family of beta-sheet stacking patterns in the fibril-like structures suggesting that the fibril structures are more complex than the corresponding crystalline structure and there exist many local free-energy minima rather than a distinct global minimum.
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Affiliation(s)
- Yan Mu
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA
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14
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Pryamitsyn V, Ganesan V. Structure of Aggregating Rod Suspensions Under Combined Shear and Electric Fields. Macromolecules 2009. [DOI: 10.1021/ma900787g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Victor Pryamitsyn
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Venkat Ganesan
- Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
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Miller CA, Gellman SH, Abbott NL, de Pablo JJ. Association of helical beta-peptides and their aggregation behavior from the potential of mean force in explicit solvent. Biophys J 2009; 96:4349-62. [PMID: 19486660 PMCID: PMC2711497 DOI: 10.1016/j.bpj.2008.11.076] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 11/20/2008] [Accepted: 11/24/2008] [Indexed: 11/19/2022] Open
Abstract
Helical beta-peptides have been shown to fold into well-defined structures. In aqueous solution, some beta-peptides self-assemble into nanoscale fibers, aggregates, and liquid crystalline phases. Molecular simulations, at an atomistic level, are used to examine, in a systematic manner, the interactions between distinct beta-peptide molecules. The relationship between side-chain chemistry (and position along the backbone) and, in particular, aggregation behaviors, is assessed by calculating the potential of mean force or dimerization free energy of two peptides in explicit water. The free energy profiles as a function of separation for helical, amphiphilic beta-peptides are consistent with experimental observations, and help explain the origins of aggregate or fiber formation in solution. Close examination of the energetic and entropic contributions to the free energy reveals that, depending on the position of certain side groups along the molecule, the tendency of two peptides to aggregate can be driven by entropy or by energy, respectively. In contrast to findings from previous works that employed a coarse representation of the solvent, it is shown that water-peptide interactions play key roles in the association behavior of beta-peptides.
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Affiliation(s)
- Clark A. Miller
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Samuel H. Gellman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Nicholas L. Abbott
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
| | - Juan J. de Pablo
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin
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16
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Padding JT. Efficient simulation of noncrossing fibers and chains in a hydrodynamic solvent. J Chem Phys 2009; 130:144903. [DOI: 10.1063/1.3105339] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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17
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Computational approaches for the design of peptides with anti-breast cancer properties. Future Med Chem 2009; 1:201-12. [DOI: 10.4155/fmc.09.13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Background: Breast cancer is the most common cancer among women. Tamoxifen is the preferred drug for estrogen receptor-positive breast cancer treatment, yet many of these cancers are intrinsically resistant to tamoxifen or acquire resistance during treatment. Therefore, scientists are searching for breast cancer drugs that have different molecular targets. Methodology: Recently, a computational approach was used to successfully design peptides that are new lead compounds against breast cancer. We used replica exchange molecular dynamics to predict the structure and dynamics of active peptides, leading to the discovery of smaller bioactive peptides. Conclusions: These analogs inhibit estrogen-dependent cell growth in a mouse uterine growth assay, a test showing reliable correlation with human breast cancer inhibition. We outline the computational methods that were tried and used along with the experimental information that led to the successful completion of this research.
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Raman SS, Vijayaraj R, Parthasarathi R, Subramanian V. Helix forming tendency of valine substituted poly-alanine: a molecular dynamics investigation. J Phys Chem B 2008; 112:9100-4. [PMID: 18597521 DOI: 10.1021/jp7119813] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this study, classical molecular dynamics simulations have been carried out on the valine (guest) substituted poly alanine (host) using the host-guest peptide approach to understand the role of valine in the formation and stabilization of helix. Valine has been substituted in the host peptide starting from N terminal to C terminal. Various structural parameters have been obtained from the molecular dynamics simulation to understand the tolerance of helical motif to valine. Depending on the position of valine in the host peptide, it stabilizes (or destabilizes) the formation of the helical structure. The substitution of valine in the poly alanine at some positions has no effect on the helix formation (deformation). It is interesting to observe the coexistence of 3 10 and alpha-helix in the peptides due to the dynamical nature of the hydrogen bonding interaction and sterical interactions.
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Affiliation(s)
- S Sundar Raman
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020 India
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Top A, Kiick KL, Roberts CJ. Modulation of self-association and subsequent fibril formation in an alanine-rich helical polypeptide. Biomacromolecules 2008; 9:1595-603. [PMID: 18452331 DOI: 10.1021/bm800056r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thermal unfolding, reversible self-association, and irreversible aggregation were investigated for an alanine-rich helical polypeptide, 17-H-6, with sequence [AAAQEAAAAQAAAQAEAAQAAQ] 6. Dynamic light scattering, transmission electron microscopy, and thermal unfolding measurements indicate that 17-H-6 spontaneously and reversibly self-associates at acidic pH and low temperature. The resulting multimers have a compact, globular morphology with an average hydrodynamic radius approximately 10-20 nm and reversibly dissociate to monomers upon an increase to pH 7.4. Both free monomer and 17-H-6 chains within the multimers are alpha-helical and folded at low temperature. Reversible unfolding of the monomer occurs upon heating of solutions at pH 7.4. At pH 2.3, heating first causes incomplete dissociation and unfolding of the constituent chains. Further incubation at elevated temperature induces additional structural and morphological changes and results in fibrils with a beta-sheet 2 degrees structure and a characteristic diameter of 5-10 nm (7 nm mean). The ability to modulate association and aggregation suggests opportunities for this class of polypeptides in nanotechnology and biomedical applications.
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Affiliation(s)
- Ayben Top
- Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
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Kirschner KN, Lexa KW, Salisburg AM, Alser KA, Joseph L, Andersen TT, Bennett JA, Jacobson HI, Shields GC. Computational design and experimental discovery of an antiestrogenic peptide derived from alpha-fetoprotein. J Am Chem Soc 2007; 129:6263-8. [PMID: 17441722 PMCID: PMC4272344 DOI: 10.1021/ja070202w] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Breast cancer is the most common cancer among women, and tamoxifen is the preferred drug for estrogen receptor-positive breast cancer treatment. Many of these cancers are intrinsically resistant to tamoxifen or acquire resistance during treatment. Consequently, there is an ongoing need for breast cancer drugs that have different molecular targets. Previous work has shown that 8-mer and cyclic 9-mer peptides inhibit breast cancer in mouse and rat models, interacting with an unsolved receptor, while peptides smaller than eight amino acids did not. We show that the use of replica exchange molecular dynamics predicts the structure and dynamics of active peptides, leading to the discovery of smaller peptides with full biological activity. Simulations identified smaller peptide analogues with the same conserved reverse turn demonstrated in the larger peptides. These analogues were synthesized and shown to inhibit estrogen-dependent cell growth in a mouse uterine growth assay, a test showing reliable correlation with human breast cancer inhibition.
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Pliego-Pastrana P, Carbajal-Tinoco MD. Two-Component Polypeptides Modeled with Effective Pair Potentials. J Phys Chem B 2006; 110:24728-33. [PMID: 17134236 DOI: 10.1021/jp0638179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present Monte Carlo simulations performed within a model based on a set of distance-dependent effective potentials which are used to describe the interactions between a pair of distinct amino acids. These effective potentials are extracted from experimental correlation functions through the Ornstein-Zernike equations and adequate closure approximations. We focus our attention on the sequences of two specific residues, namely, alanine and glycine. The studied sequences are (a) (Ala)(12)-(Gly)(4)-(Ala)(12) and (b) three interacting chains of alternating alanines and glycines (with five residues per chain). The resulting structures are combinations of known secondary structures. More importantly, we verify that our simulated structures are in thermodynamic equilibrium by means of an estimation of the density of states.
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Affiliation(s)
- P Pliego-Pastrana
- Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 México D.F., Mexico
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