(2S,4R)- and (2S,4S)-Perfluoro-tert-butyl 4-Hydroxyproline: Two Conformationally Distinct Proline Amino Acids for Sensitive Application in 19F NMR

Tressler, Caitlin M.; Zondlo, Neal J.

doi:10.1021/jo5008674

Cited by 38 publications

(58 citation statements)

References 69 publications

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“…96 However, these would also have poor NMR properties due to a large coupling between the fluorine atoms. 94 Alternatively, Tressler and Zondlo adapted the use of perfluoro-tert-butytoxy 19 F probes 97,98 and proposed the use of O-perfluoro-tert-butyl-4-hydroxyprolines in NMR applications, 99 although these bulky lipophilic compounds also demonstrated a significant conformational bias in trans/cis amide equilibrium. Other proposed Pro substitutes are trifluoromethyl-4,5-methanoprolines, which were originally introduced as 19 F NMR labels for solid-state NMR studies in lipid membranes.…”

Section: Discussionmentioning

confidence: 99%

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

2018

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Section: Discussionmentioning

confidence: 99%

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

2018

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“…As an initial test, 4 was incorporated within a model peptide (Ac-GPPXPPGY-NH 2 ) that has been previously employed to quantify the polyproline II helix propensities of both canonical and unnatural amino acids. [43][44][45][46][47][48] Using bulk resulting from β-substitution with the sulfone. [49,50] However, amide coupling proceeded effectively using COMU as a coupling reagent [51] in the presence of catalytic DMAP (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of peptides with cysteine sulfinic acid via the cysteine methoxybenzyl sulfone

Urmey

Zondlo

2019

Peptide Science

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Cysteine sulfinic acid is a protein posttranslational modification that is formed under oxidative conditions and is regulated both enzymatically and nonenzymatically. Cysteine oxidation to the sulfinic acid has been observed broadly throughout the proteome and can induce activation or inhibition of function in proteins. Recently, wide‐scale, reversible regulation of the sulfinic acid state of cysteine within proteins was identified, posing new questions in cysteine sulfinic acid biology. Existing methods to synthesize peptides with cysteine sulfinic acid can suffer from low yield, due to the formation of side products in the disulfide, sulfenic acid, and/or sulfonic acid oxidation states. Herein, a method for the synthesis of peptides with cysteine sulfinic acids was developed, via protection of cysteine sulfinic acid as the methoxybenzyl (Mob) sulfone. Cysteine Mob sulfone was synthesized as an Fmoc amino acid in one step from the commercially available Mob‐protected Fmoc‐cysteine (Fmoc‐Cys(Mob)‐OH). This amino acid was directly incorporated into peptides via solid‐phase peptide synthesis. Alternatively, peptides were synthesized using Fmoc‐Cys(Mob)‐OH, followed by subsequent oxidation within peptides of the thioether to the Mob sulfone via H2O2 and catalytic niobium carbide. Deprotection of peptides under strongly acidic conditions (50% triflic acid, 45% trifluoroacetic acid, 5% water) generated peptides with cysteine sulfinic acid. This approach was applied to the synthesis of peptides containing cysteine sulfinic acid within diverse peptide sequence contexts.

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“…The key step of the synthesis is the Mitsunobu reaction of the homoserine side chain alcohol with perfluoro- tert -butanol, as was used previously in the synthesis of perfluoro- tert -butyl hydroxyprolines and other described perfluoro- tert -butyl ethers. (75, 100–102, 111)…”

Section: Resultsmentioning

confidence: 99%

“…(100, 104–106) The coupling constant 3 J αN , which correlates with the ϕ torsion angle via a parametrized Karplus equation,(107) was calculated for perfluoro- tert -butyl homoserine in peptides in order to directly examine the effects of this amino acid on ϕ in different peptide contexts. Resonance assignments were obtained via TOCSY spectra.…”

Section: Methodsmentioning

confidence: 99%

Perfluoro-tert-butyl Homoserine Is a Helix-Promoting, Highly Fluorinated, NMR-Sensitive Aliphatic Amino Acid: Detection of the Estrogen Receptor·Coactivator Protein–Protein Interaction by ¹⁹F NMR

Tressler

Zondlo

2017

Biochemistry

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Highly fluorinated amino acids can stabilize proteins and complexes with proteins, via enhanced hydrophobicity, and provide novel methods for identification of specific molecular events in complex solutions, via selective detection by 19F NMR and the absence of native 19F signals in biological contexts. However, the potential applications of 19F NMR in probing biological processes are limited both by the strong propensities of most highly fluorinated amino acids for the extended conformation and by the relatively modest sensitivity of NMR spectroscopy, which typically constrains measurements to mid-micromolar concentrations. Herein, we demonstrate that perfluoro-tert-butyl homoserine exhibits a propensity for compact conformations, including α-helix and polyproline helix (PPII), that is similar to that of methionine. Perfluoro-tert-butyl homoserine has 9 equivalent fluorines that do not couple to any other nuclei, resulting in a sharp singlet that can be sensitively detected rapidly at low micromolar concentrations. Perfluoro-tert-butyl homoserine was incorporated at sites of leucine residues within the α-helical LXXLL short linear motif of estrogen receptor (ER) co-activator peptides. A peptide containing perfluoro-tert-butyl homoserine at the i+3 position of the ER coactivator LXXLL motif exhibited Kd = 2.2 μM for the estradiol-bound estrogen receptor, similar to that of the native ligand. 19F NMR spectroscopy demonstrated the sensitive detection (5 μM concentration, 128 scans) of peptide binding to ER and of inhibition of protein-protein interaction by the native ligand or by the ER antagonist tamoxifen. These results suggest diverse potential applications of perfluoro-tert-butyl homoserine to probe protein function and protein-protein interfaces in complex solutions.

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(2S,4R)- and (2S,4S)-Perfluoro-tert-butyl 4-Hydroxyproline: Two Conformationally Distinct Proline Amino Acids for Sensitive Application in ¹⁹F NMR

Cited by 38 publications

References 69 publications

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

Synthesis of peptides with cysteine sulfinic acid via the cysteine methoxybenzyl sulfone

Perfluoro-tert-butyl Homoserine Is a Helix-Promoting, Highly Fluorinated, NMR-Sensitive Aliphatic Amino Acid: Detection of the Estrogen Receptor·Coactivator Protein–Protein Interaction by ¹⁹F NMR

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(2S,4R)- and (2S,4S)-Perfluoro-tert-butyl 4-Hydroxyproline: Two Conformationally Distinct Proline Amino Acids for Sensitive Application in 19F NMR

Cited by 38 publications

References 69 publications

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

Comparative effects of trifluoromethyl- and methyl-group substitutions in proline

Synthesis of peptides with cysteine sulfinic acid via the cysteine methoxybenzyl sulfone

Perfluoro-tert-butyl Homoserine Is a Helix-Promoting, Highly Fluorinated, NMR-Sensitive Aliphatic Amino Acid: Detection of the Estrogen Receptor·Coactivator Protein–Protein Interaction by 19F NMR

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Product

Resources

About

(2S,4R)- and (2S,4S)-Perfluoro-tert-butyl 4-Hydroxyproline: Two Conformationally Distinct Proline Amino Acids for Sensitive Application in ¹⁹F NMR

Perfluoro-tert-butyl Homoserine Is a Helix-Promoting, Highly Fluorinated, NMR-Sensitive Aliphatic Amino Acid: Detection of the Estrogen Receptor·Coactivator Protein–Protein Interaction by ¹⁹F NMR