DNA cyclization is potentially the most powerful approach for systematic quantitation of sequence-dependent DNA bending and flexibility. We extend the statistical mechanics of the homogeneous DNA circle to a model that considers discrete basepairs, thus allowing for inhomogeneity, and apply the model to analysis of DNA cyclization. The theory starts from an iterative search for the minimum energy configuration of circular DNA. Thermodynamic quantities such as the J factor, which is essentially the ratio of the partition functions of circular and linear forms, are evaluated by integrating the thermal fluctuations around the configuration under harmonic approximation. Accurate analytic expressions are obtained for equilibrium configurations of homogeneous circular DNA with and without bending anisotropy. J factors for both homogeneous and inhomogeneous DNA are evaluated. Effects of curvature, helical repeat, and bending and torsional flexibility in DNA cyclization are analyzed in detail, revealing that DNA cyclization can detect as little as one degree of curvature and a few percent change in flexibility. J factors calculated by our new approach are well consistent with Monte Carlo simulations, whereas the new theory has much greater efficiency in computations. Simulation of experimental results has been demonstrated.
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http://dx.doi.org/10.1016/S0006-3495(03)74838-3 | DOI Listing |
Org Lett
January 2025
Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China.
We here report an efficient DNA-compatible furan-thiol-amine reaction for macrocyclization and late-stage amine transformation. This reaction, conducted under mild conditions, enables the facile cyclization of DNA-conjugated linear peptides into thiopyrrole-grafted macrocycles regardless of ring size or side-chain modification with good to excellent conversion yields. Additionally, this strategy was employed for the late-stage transformation of terminal amines, serving as critical intermediates in the construction of DNA-encoded peptide libraries.
View Article and Find Full Text PDFBioorg Med Chem Lett
December 2024
Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan. Electronic address:
At present, mid-sized binding peptides have emerged as a new class of drug modalities. We have de novo designed a helix-loop-helix (HLH) peptide (MW: ∼4,500), constructed phage-displayed libraries, and screened the libraries against a variety of disease-related proteins to successfully obtain molecular-targeting HLH peptides. The next essential step in developing HLH peptides into therapeutics involves affinity engineering to optimize binding affinity and specificity.
View Article and Find Full Text PDFBiochemistry
December 2024
Department of Molecular Biology and Genetics, Aarhus University, Universitetsbyen 81, Aarhus C DK-8000, Denmark.
DNA-encoded libraries hold great potential for discovering small, cyclized peptides with drug potential. Split-intein circular ligation of peptides and proteins (SICLOPPS) is a well-established method for selection of cyclic peptides targeting specific intracellular components. However, the method has mainly been used in prokaryotic cells.
View Article and Find Full Text PDFJ Biomol Struct Dyn
November 2024
Molecular and Biophysical Research Lab (MBRL), Department of Chemistry, Jamia Millia Islamia, New Delhi, India.
Pyrazoline derivatives () and () were designed and synthesized through chalcones () cyclization with NHNH/HCOOH and NHCSNHNH/CHCOOH, respectively. The molecular structures were elucidated by using various techniques such as UV-visible, FT-IR, H, C NMR spectroscopy and mass spectrometry. The purity of all synthesized compounds was checked by the liquid chromatography-mass spectrometry (LC-MS).
View Article and Find Full Text PDFOrg Lett
December 2024
HitGen Inc., Building 6, No. 8 Huigu 1st East Road, Tianfu International Bio-Town, Shuangliu District, Chengdu 610200, Sichuan, P. R. China.
DNA-encoded library (DEL) technology has been developed to serve as a practical platform for the discovery of biologically active macrocyclic peptide compounds. However, the cyclization of linear peptides has been widely regarded as the challenging step in the production of macrocyclic peptide DELs. Herein, we describe a novel DNA-compatible macrocyclization strategy, which enables the construction of ring systems via visible-light-mediated desulfurative C-C bond formation.
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