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Lal J, Kaul G, Akhir A, Saxena D, Dubkara H, Shekhar S, Chopra S, Reddy DN. β-Turn editing in Gramicidin S: Activity impact on replacing proline α-carbon with stereodynamic nitrogen. Bioorg Chem 2023; 138:106641. [PMID: 37300963 DOI: 10.1016/j.bioorg.2023.106641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/15/2023] [Accepted: 05/26/2023] [Indexed: 06/12/2023]
Abstract
Gramicidin S, natural antimicrobial peptide is used commercially in medicinal lozenges for sore throat and Gram-negative and Gram-positive bacterial infections. However, its clinical potential is limited to topical applications because of its high red blood cells (RBC) cytotoxicity. Given the importance of developing potential antibiotics and inspired by the cyclic structure and druggable features of Gramicidin S, we edited proline α-carbon with stereodynamic nitrogen to examine the direct impact on biological activity and cytotoxicity with respect to prolyl counterpart. Natural Gramicidin S (12), proline-edited peptides 13-16 and wild-type d-Phe-d-Pro β-turn mimetics (17 and 18) were synthesized using solid phase peptide synthesis and investigated their activity against clinically relevant bacterial pathogens. Interestingly, mono-proline edited analogous peptide 13 showed moderate improvement in antimicrobial activity against E. coli ATCC 25922 and K.pneumoniae BAA 1705 as compared to Gramicidin S. Furthermore, proline edited peptide 13 exhibited equipotent antimicrobial effect against MDR S. aureus and Enterococcus spp. Analysis of cytotoxicity against VERO cells and RBC, reveals that proline edited peptides showed two-fivefold lesser cytotoxicity than the counterpart Gramicidin S. Our study suggests that introducing single azPro/Pro mutation in Gramicidin S marginally improved the activity and lessens the cytotoxicity as compared with the parent peptide.
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Affiliation(s)
- Jhajan Lal
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow 226031, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP 201002, India
| | - Grace Kaul
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP 201002, India
| | - Abdul Akhir
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Deepanshi Saxena
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Harshita Dubkara
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow 226031, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP 201002, India
| | - Shashank Shekhar
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow 226031, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP 201002, India
| | - Sidharth Chopra
- Division of Molecular Microbiology and Immunology, CSIR-Central Drug Research Institute, Lucknow 226031, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP 201002, India.
| | - Damodara N Reddy
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow 226031, India; Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP 201002, India.
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2
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Lal J, Prajapati G, Meena R, Kant R, Sankar Ampapathi R, Reddy DN. Influence of Proline Chirality on Neighbouring Azaproline Residue Stereodynamic Nitrogen Preorganization. Chem Asian J 2023; 18:e202201023. [PMID: 36349404 DOI: 10.1002/asia.202201023] [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: 10/06/2022] [Revised: 11/04/2022] [Indexed: 11/10/2022]
Abstract
We report herein the first systematic crystal structural investigation of azaproline incorporated in homo- and heterochiral diprolyl peptides. The X-ray crystallography data of peptides 1-5 illustrates that stereodynamic nitrogen in azaproline adopted the stereochemistry of neighbouring proline residue without depending on its position in the peptide sequence. Natural bond orbital analysis of crystal structures indicates OazPro -C'Pro of peptides 4 and 5 participating in n→π* interaction with stabilization energy about 1.21-1.33 kcal/mol. Density functional theory calculations suggested that the endo-proline ring puckering favoured over exo-conformation by 6.72-7.64 kcal/mol. NBO and DFT data reveals that the n→π* interactions and proline ring puckering stabilize azaproline chirality with the neighbouring proline stereochemistry. The CD, solvent titration, variable-temperature and 2D NMR experimental results further supported the crystal structures conformation.
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Affiliation(s)
- Jhajan Lal
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow, 226031, India) .,Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP-201002, India
| | - Gurudayal Prajapati
- Division of Sophisticated Analytical Instrument Facility and Research, CSIR-CDRI, Lucknow, 226031, India.,Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP-201002, India
| | - Rachana Meena
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow, 226031, India) .,Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP-201002, India
| | - Ruchir Kant
- Biochemistry and Structural Biology Division, CSIR-CDRI, Lucknow, 226031, India
| | - Ravi Sankar Ampapathi
- Division of Sophisticated Analytical Instrument Facility and Research, CSIR-CDRI, Lucknow, 226031, India.,Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP-201002, India
| | - Damodara N Reddy
- Division of Medicinal and Process Chemistry, CSIR-CDRI, Lucknow, 226031, India) .,Academy of Scientific & Innovative Research (AcSIR), Ghaziabad, UP-201002, India
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3
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Kashif Khan R, Meanwell NA, Hager HH. Pseudoprolines as stereoelectronically tunable proline isosteres. Bioorg Med Chem Lett 2022; 75:128983. [PMID: 36096342 DOI: 10.1016/j.bmcl.2022.128983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 08/29/2022] [Accepted: 09/05/2022] [Indexed: 11/18/2022]
Abstract
The cyclic structure of proline (Pro) confers unique conformational properties on this natural amino acid that influences polypeptide structure and function. Pseudoprolines are a family of Pro isosteres that incorporate a heteroatom, most prominently oxygen or sulfur but also silicon and selenium, to replace the Cβ or Cγ carbon atom of the pyrrolidine ring. These readily synthetically accessible structural motifs can facilitate facile molecular editing in a fashion that allows modulation of the amide bond topology of dipeptide elements and influence over ring pucker. While the properties of pseudoprolines have been exploited most prominently in the design of oligopeptide analogues, they have potential application in the design and optimization of small molecules. In this Digest, we summarize the physicochemical properties of pseudoprolines and illustrate their potential in drug discovery by surveying examples of applications in the design of bioactive molecules.
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Affiliation(s)
- R Kashif Khan
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, 100 Binney Street, Cambridge, MA 02142, USA.
| | - Nicholas A Meanwell
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, P.O. Box 4000, Princeton, NJ 08543-4000, USA.
| | - Harry H Hager
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, 200 Cambridgepark Drive, Cambridge, MA 02140, USA.
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4
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Abstract
The carbonyl group holds a prominent position in chemistry and biology not only because it allows diverse transformations but also because it supports key intermolecular interactions, including hydrogen bonding. More recently, carbonyl groups have been found to interact with a variety of nucleophiles, including other carbonyl groups, in what we have termed an n→π* interaction. In an n→π* interaction, a nucleophile donates lone-pair (n) electron density into the empty π* orbital of a nearby carbonyl group. Mixing of these orbitals releases energy, resulting in an attractive interaction. Hints of such interactions were evident in small-molecule crystal structures as early as the 1970s, but not until 2001 was the role of such interactions articulated clearly. These non-covalent interactions were first discovered during investigations into the thermostability of the proline-rich protein collagen, which achieves a robust structure despite a relatively low potential for hydrogen bonding. It was found that by modulating the distance between two carbonyl groups in the peptide backbone, one could alter the conformational preferences of a peptide bond to proline. Specifically, only the trans conformation of a peptide bond to proline allows for an attractive interaction with an adjacent carbonyl group, so when one increases the proximity of the two carbonyl groups, one enhances their interaction and promotes the trans conformation of the peptide bond, which increases the thermostability of collagen. More recently, attention has been paid to the nature of these interactions. Some have argued that rather than resulting from electron donation, carbonyl interactions are a particular example of dipolar interactions that are well-approximated by classical mechanics. However, experimental evidence has demonstrated otherwise. Numerous examples now exist where an increase in the dipole moment of a carbonyl group decreases the strength of its interactions with other carbonyl groups, demonstrating unequivocally that a dipolar mechanism is insufficient to describe these interactions. Rather, these interactions have important quantum-mechanical character that can be evaluated through careful experimental analysis and judicious use of computation. Although individual n→π* interactions are relatively weak (∼0.3-0.7 kcal/mol), the ubiquity of carbonyl groups across chemistry and biology gives the n→π* interaction broad impact. In particular, the n→π* interaction is likely to play an important role in dictating protein structure. Indeed, bioinformatics analysis suggests that approximately one-third of residues in folded proteins satisfy the geometric requirements to engage in an n→π* interaction, which is likely to be of particular importance for the α-helix. Other carbonyl-dense polymeric materials like polyesters and peptoids are also influenced by n→π* interactions, as are a variety of small molecules, some with particular medicinal importance. Research will continue to identify molecules whose conformation and activity are affected by the n→π* interaction and will clarify their specific contributions to the structures of biomacromolecules.
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Affiliation(s)
- Robert W. Newberry
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Ronald T. Raines
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
- Department
of Biochemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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5
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Park HS, Kang YK. Effects of isosteric substitutions on the conformational preference and cis–trans isomerization of proline-containing peptides. NEW J CHEM 2017. [DOI: 10.1039/c7nj01403a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Isosteric substitutions of the peptide CO group by CS and CSe groups increased thetranspopulation and rotational barrier to the prolylcis–transisomerization of proline-containing peptides.
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Affiliation(s)
- Hae Sook Park
- Department of Nursing
- Cheju Halla University
- Cheju 63092
- Republic of Korea
| | - Young Kee Kang
- Department of Chemistry and BK21 PLUS Research Team
- Chungbuk National University
- Cheongju
- Republic of Korea
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6
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Kheria S, Nair RV, Kotmale AS, Rajamohanan PR, Sanjayan GJ. The role of N-terminal proline in stabilizing the Ant–Pro zipper motif. NEW J CHEM 2015. [DOI: 10.1039/c4nj02151g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper deals with the role of N-terminal proline in stabilizing the Ant–Pro zipper structure by the co-operative contribution of competing forces viz. hydrogen bonding, aromatic stacking and backbone chirality.
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Affiliation(s)
- Sanjeev Kheria
- Division of Organic Chemistry
- National Chemical Laboratory
- Pune 411 008
- India
| | - Roshna V. Nair
- Division of Organic Chemistry
- National Chemical Laboratory
- Pune 411 008
- India
| | - Amol S. Kotmale
- Central NMR Facility
- National Chemical Laboratory
- Pune 411 008
- India
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Huang S, Wu R, Bai Z, Yang Y, Li S, Dou X. Evaluation of the separation performance of polyvinylpyrrolidone as a virtual stationary phase for chromatographic NMR. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2014; 52:486-490. [PMID: 24975777 DOI: 10.1002/mrc.4102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 06/06/2014] [Accepted: 06/09/2014] [Indexed: 06/03/2023]
Abstract
Polyvinylpyrrolidone (PVP) was used as a virtual stationary phase to separate p-xylene, benzyl alcohol, and p-methylphenol by the chromatographic NMR technique. The effects of concentration and weight-average molecular weight (Mw) of PVP, solvent viscosity, solvent polarity, and sample temperature on the resolution of these components were investigated. It was found that both higher PVP concentration and higher PVP Mw caused the increase of diffusion resolution for the three components. Moreover, the diffusion resolution did not change at viscosity-higher solvents. Moreover, the three components showed different resolution at different solvents. As temperature increased, the diffusion resolution between p-xylene and benzyl alcohol gradually increased, and the one between p-xylene and p-methylphenol slightly increased from 278 to 298 K and then decreased above 298 K. It was also found that the polarity of the analytes played an important role for the separation by affecting the diffusion coefficient.
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Affiliation(s)
- Shaohua Huang
- Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
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8
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Tumminakatti S, Reddy DN, Lakshmi AN, Prabhakaran EN. Synthesis of 5,6-dihydro-4H-1,3-thiazine containing peptide mimics from N-(3-hydroxypropyl)thioamides and epimerization studies. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2014.06.084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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9
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Reddy DN, Prabhakaran EN. Steric and electronic interactions controlling the cis/trans isomer equilibrium at X-pro tertiary amide motifs in solution. Biopolymers 2013; 101:66-77. [DOI: 10.1002/bip.22278] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 04/27/2013] [Indexed: 11/11/2022]
Affiliation(s)
- Damodara N. Reddy
- Department of Organic Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
| | - Erode N. Prabhakaran
- Department of Organic Chemistry; Indian Institute of Science; Bangalore 560012 Karnataka India
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