The binding of a 13C-labeled cyclosporin A (CsA) analog to cyclophilin (peptidyl prolyl isomerase) was examined by means of isotope-edited nuclear magnetic resonance (NMR) techniques. A trans 9,10 peptide bond was adopted when CsA was bound to cyclophilin, in contrast to the cis 9,10 peptide bond found in the crystalline and solution conformations of CsA. Furthermore, nuclear Overhauser effects (NOEs) were observed between the zeta 3 and epsilon 3 protons of the methylleucine (MeLeu) residue at position 9 of CsA and tryptophan121 (Trp121) and phenylalanine (Phe) protons of cyclophilin, suggesting that the MeLeu9 residue of CsA interacts with cyclophilin. These results illustrate the power of isotope-edited NMR techniques for rapidly providing useful information about the conformations and active site environment of inhibitors bound to their target enzymes.
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http://dx.doi.org/10.1126/science.2255910 | DOI Listing |
J Phys Chem B
April 2021
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
J Biomol NMR
December 2020
Department of Structural Biology, Weizmann Institute of Science, 76100, Rehovot, Israel.
Many proteins interact with their ligand proteins by recognition of short linear motifs that are often intrinsically disordered. These interactions are usually weak and are characterized by fast exchange. NMR spectroscopy is a powerful tool to study weak interactions.
View Article and Find Full Text PDFACS Chem Biol
May 2020
Department of Chemistry, Stanford University, Stanford, California 94305-5012, United States.
A biophysical understanding of the mechanistic, chemical, and physical origins underlying antibiotic action and resistance is vital to the discovery of novel therapeutics and the development of strategies to combat the growing emergence of antibiotic resistance. The site-specific introduction of stable-isotope labels into chemically complex natural products is particularly important for techniques such as NMR, IR, mass spectrometry, imaging, and kinetic isotope effects. Toward this goal, we developed a biosynthetic strategy for the site-specific incorporation of C labels into the canonical β-lactam carbonyl of penicillin G and cefotaxime, the latter via cephalosporin C.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
March 2020
Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695;
Peptide self-assembly, wherein molecule A associates with other A molecules to form fibrillar β-sheet structures, is common in nature and widely used to fabricate synthetic biomaterials. Selective coassembly of peptide pairs A and B with complementary partial charges is gaining interest due to its potential for expanding the form and function of biomaterials that can be realized. It has been hypothesized that charge-complementary peptides organize into alternating ABAB-type arrangements within assembled β-sheets, but no direct molecular-level evidence exists to support this interpretation.
View Article and Find Full Text PDFBiochemistry
September 2019
Department of Chemistry , University of Hawaii, 2545 McCarthy Mall , Honolulu , Hawaii 96822 , United States.
Samples of native elastin are prepared with high levels of enrichment at its prolines, which are believed to play a major role in the elasticity of elastin. Major and minor populations of and isomers at the Xaa-Pro imide bonds are detected in two-dimensional C nuclear magnetic resonance (NMR) experiments. One- and two-dimensional C NMR and isotope-edited Fourier transform infrared experiments are also used to identify the prolines' folded and unfolded states, type II β-turn and random coil, respectively, at physiological temperatures.
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