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Teixeira LGD, Malavolta L, Bersanetti PA, Schreier S, Carmona AK, Nakaie CR. Paramagnetic bradykinin analogues as substrates for angiotensin I-converting enzyme: Pharmacological and conformation studies. Bioorg Chem 2016; 69:159-166. [PMID: 27837711 DOI: 10.1016/j.bioorg.2016.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/10/2016] [Accepted: 10/26/2016] [Indexed: 11/27/2022]
Abstract
This study uses EPR, CD, and fluorescence spectroscopy to examine the structure of bradykinin (BK) analogues attaching the paramagnetic amino acid-type Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at positions 0, 3, 7, and 9. The data were correlated with the potencies in muscle contractile experiments and the substrate properties towards the angiotensin I-converting enzyme (ACE). A study of the biological activities in guinea pig ileum and rat uterus indicated that only Toac0-BK partially maintained its native biological potency among the tested peptides. This and its counterpart, Toac3-BK, maintained the ability to act as ACE substrates. These results indicate that peptides bearing Toac probe far from the ACE cleavage sites were more susceptible to hydrolysis by ACE. The results also emphasize the existence of a finer control for BK-receptor interaction than for BK binding at the catalytic site of this metallodipetidase. The kinetic kcat/Km values decreased from 202.7 to 38.9μM-1min-1 for BK and Toac3-BK, respectively. EPR, CD, and fluorescence experiments reveal a direct relationship between the structure and activity of these paramagnetic peptides. In contrast to the turn-folded structures of the Toac-internally labeled peptides, more extended conformations were displayed by N- or C-terminally Toac-labeled analogues. Lastly, this work supports the feasibility of monitoring the progress of the ACE-hydrolytic process of Toac-attached peptides by examining time-dependent EPR spectral variations.
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Affiliation(s)
- Luis Gustavo Deus Teixeira
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, 04044-020 Sao Paulo, SP, Brazil
| | - Luciana Malavolta
- Department of Physiological Sciences, Santa Casa de Sao Paulo, School of Medical Sciences, 01221-020 Sao Paulo, SP, Brazil
| | | | - Shirley Schreier
- Department of Biochemistry, Institute of Chemistry, Universidade de Sao Paulo, 05513-970 Sao Paulo, SP, Brazil
| | - Adriana K Carmona
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, 04044-020 Sao Paulo, SP, Brazil
| | - Clovis R Nakaie
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, 04044-020 Sao Paulo, SP, Brazil.
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Abstract
Site-directed spin labeling (SDSL) in combination with electron paramagnetic resonance (EPR) spectroscopy is a well-established method that has recently grown in popularity as an experimental technique, with multiple applications in protein and peptide science. The growth is driven by development of labeling strategies, as well as by considerable technical advances in the field, that are paralleled by an increased availability of EPR instrumentation. While the method requires an introduction of a paramagnetic probe at a well-defined position in a peptide sequence, it has been shown to be minimally destructive to the peptide structure and energetics of the peptide-membrane interactions. In this chapter, we describe basic approaches for using SDSL EPR spectroscopy to study interactions between small peptides and biological membranes or membrane mimetic systems. We focus on experimental approaches to quantify peptide-membrane binding, topology of bound peptides, and characterize peptide aggregation. Sample preparation protocols including spin-labeling methods and preparation of membrane mimetic systems are also described.
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Affiliation(s)
- Tatyana I Smirnova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA.
| | - Alex I Smirnov
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
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Teixeira LGD, Malavolta L, Bersanetti PA, Schreier S, Carmona AK, Nakaie CR. Conformational Properties of Seven Toac-Labeled Angiotensin I Analogues Correlate with Their Muscle Contraction Activity and Their Ability to Act as ACE Substrates. PLoS One 2015; 10:e0136608. [PMID: 26317625 PMCID: PMC4552746 DOI: 10.1371/journal.pone.0136608] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/06/2015] [Indexed: 11/18/2022] Open
Abstract
Conformational properties of the angiotensin II precursor, angiotensin I (AngI) and analogues containing the paramagnetic amino acid TOAC (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at positions 0, 1, 3, 5, 8, 9, and 10, were examined by EPR, CD, and fluorescence. The conformational data were correlated to their activity in muscle contraction experiments and to their properties as substrates of the angiotensin I-converting enzyme (ACE). Biological activity studies indicated that TOAC0-AngI and TOAC1-AngI maintained partial potency in guinea pig ileum and rat uterus. Kinetic parameters revealed that only derivatives labeled closer to the N-terminus (positions 0, 1, 3, and 5) were hydrolyzed by ACE, indicating that peptides bearing the TOAC moiety far from the ACE cleavage site (Phe8-His9 peptide bond) were susceptible to hydrolysis, albeit less effectively than the parent compound. CD spectra indicated that AngI exhibited a flexible structure resulting from equilibrium between different conformers. While the conformation of N-terminally-labeled derivatives was similar to that of the native peptide, a greater propensity to acquire folded structures was observed for internally-labeled, as well as C-terminally labeled, analogues. These structures were stabilized in secondary structure-inducing agent, TFE. Different analogues gave rise to different β-turns. EPR spectra in aqueous solution also distinguished between N-terminally, internally-, and C-terminally labeled peptides, yielding narrower lines, indicative of greater mobility for the former. Interestingly, the spectra of peptides labeled at, or close, to the C-terminus, showed that the motion in this part of the peptides was intermediate between that of N-terminally and internally-labeled peptides, in agreement with the suggestion of turn formation provided by the CD spectra. Quenching of the Tyr4 fluorescence by the differently positioned TOAC residues corroborated the data obtained by the other spectroscopic techniques. Lastly, we demonstrated the feasibility of monitoring the progress of ACE-catalyzed hydrolysis of TOAC-labeled peptides by following time-dependent changes in their EPR spectra.
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Affiliation(s)
- Luis Gustavo D Teixeira
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Luciana Malavolta
- Department of Physiological Sciences, Santa Casa de Sao Paulo School of Medical Sciences, Sao Paulo, Sao Paulo, Brazil
| | - Patrícia A Bersanetti
- Department of Health and Informatics, Universidade Federal de São Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Shirley Schreier
- Department of Biochemistry, Institute of Chemistry, Universidade de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Adriana K Carmona
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Clovis R Nakaie
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, Sao Paulo, Brazil
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Vieira RDFF, Nardi DT, Nascimento N, Rosa JC, Nakaie CR. Peptide Structure Modifications: Effect of Radical Species Generated by Controlled Gamma Ray Irradiation Approach. Biol Pharm Bull 2013; 36:664-75. [DOI: 10.1248/bpb.b12-01036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Daniela Teves Nardi
- Department of Biophysics, Paulista Medical School, Federal University of Sao Paulo
| | - Nanci Nascimento
- Nuclear and Energy Research Institute (IPEN), University of Sao Paulo (USP)
| | - José César Rosa
- Protein Chemistry Center and Department of Molecular and Cell Biology, Ribeirao Preto Medical School, University of Sao Paulo (USP)
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Short peptide constructs mimic agonist sites of AT(1)R and BK receptors. Amino Acids 2012; 44:835-46. [PMID: 23096780 DOI: 10.1007/s00726-012-1405-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 09/17/2012] [Indexed: 10/27/2022]
Abstract
Extracellular peptide ligand binding sites, which bind the N-termini of angiotensin II (AngII) and bradykinin (BK) peptides, are located on the N-terminal and extracellular loop 3 regions of the AT(1)R and BKRB(1) or BKRB(2) G-protein-coupled receptors (GPCRs). Here we synthesized peptides P15 and P13 corresponding to these receptor fragments and showed that only constructs in which these peptides were linked by S-S bond, and cyclized by closing the gap between them, could bind agonists. The formation of construct-agonist complexes was revealed by electron paramagnetic resonance spectra and fluorescence measurements of spin labeled biologically active analogs of AngII and BK (Toac(1)-AngII and Toac(0)-BK), where Toac is the amino acid-type paramagnetic and fluorescence quencher 2, 2, 6, 6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid. The inactive derivatives Toac(3)-AngII and Toac(3)-BK were used as controls. The interactions characterized by a significant immobilization of Toac and quenching of fluorescence in complexes between agonists and cyclic constructs were specific for each system of peptide-receptor construct assayed since no crossed reactions or reaction with inactive peptides could be detected. Similarities among AT, BKR, and chemokine receptors were identified, thus resulting in a configuration for AT(1)R and BKRB cyclic constructs based on the structure of the CXCR(4), an α-chemokine GPCR-type receptor.
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Gao T, Petrlova J, He W, Huser T, Kudlick W, Voss J, Coleman MA. Characterization of de novo synthesized GPCRs supported in nanolipoprotein discs. PLoS One 2012; 7:e44911. [PMID: 23028674 PMCID: PMC3460959 DOI: 10.1371/journal.pone.0044911] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/09/2012] [Indexed: 02/05/2023] Open
Abstract
The protein family known as G-protein coupled receptors (GPCRs) comprises an important class of membrane-associated proteins, which remains a difficult family of proteins to characterize because their function requires a native-like lipid membrane environment. This paper focuses on applying a single step method leading to the formation of nanolipoprotein particles (NLPs) capable of solubilizing functional GPCRs for biophysical characterization. NLPs were used to demonstrate increased solubility for multiple GPCRs such as the Neurokinin 1 Receptor (NK1R), the Adrenergic Receptor â2 (ADRB2) and the Dopamine Receptor D1 (DRD1). All three GPCRs showed affinity for their specific ligands using a simple dot blot assay. The NK1R was characterized in greater detail to demonstrate correct folding of the ligand pocket with nanomolar specificity. Electron paramagnetic resonance (EPR) spectroscopy validated the correct folding of the NK1R binding pocket for Substance P (SP). Fluorescence correlation spectroscopy (FCS) was used to identify SP-bound NK1R-containing NLPs and measure their dissociation rate in an aqueous environment. The dissociation constant was found to be 83 nM and was consistent with dot blot assays. This study represents a unique combinational approach involving the single step de novo production of a functional GPCR combined with biophysical techniques to demonstrate receptor association with the NLPs and binding affinity to specific ligands. Such a combined approach provides a novel path forward to screen and characterize GPCRs for drug discovery as well as structural studies outside of the complex cellular environment.
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Affiliation(s)
- Tingjuan Gao
- NSF Center for Biophotonics Science and Technology, University of California Davis Medical Center, Sacramento, California, United States of America
- Department of Biochemistry and Molecular Medicine, University of California Davis Medical Center, Sacramento, California, United States of America
| | - Jitka Petrlova
- Department of Biochemistry and Molecular Medicine, University of California Davis Medical Center, Sacramento, California, United States of America
| | - Wei He
- Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, California, United States of America
| | - Thomas Huser
- NSF Center for Biophotonics Science and Technology, University of California Davis Medical Center, Sacramento, California, United States of America
| | - Wieslaw Kudlick
- Life Technologies, Carlsbad, California, United States of America
| | - John Voss
- Department of Biochemistry and Molecular Medicine, University of California Davis Medical Center, Sacramento, California, United States of America
- * E-mail: (JV); (MAC)
| | - Matthew A. Coleman
- NSF Center for Biophotonics Science and Technology, University of California Davis Medical Center, Sacramento, California, United States of America
- Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, California, United States of America
- Lawrence Livermore National Laboratory, Livermore, California, United States of America
- * E-mail: (JV); (MAC)
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The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects. Biophys Rev 2012; 4:45-66. [PMID: 22347893 PMCID: PMC3271205 DOI: 10.1007/s12551-011-0064-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 12/20/2011] [Indexed: 01/21/2023] Open
Abstract
We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides and peptide synthesis. TOAC was the first spin label probe incorporated in peptides by means of a peptide bond. In view of the rigid character of this cyclic molecule and its attachment to the peptide backbone via a peptide bond, TOAC incorporation has been very useful to analyze backbone dynamics and peptide secondary structure. Many of these studies were performed making use of EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, and FT-IR, have been employed. The use of double-labeled synthetic peptides has allowed the investigation of their secondary structure. A large number of studies have focused on the interaction of peptides, both synthetic and biologically active, with membranes. In the latter case, work has been reported on ligands and fragments of GPCR, host defense peptides, phospholamban, and β-amyloid. EPR studies of macroscopically aligned samples have provided information on the orientation of peptides in membranes. More recent studies have focused on peptide–protein and peptide–nucleic acid interactions. Moreover, TOAC has been shown to be a valuable probe for paramagnetic relaxation enhancement NMR studies of the interaction of labeled peptides with proteins. The growth of the number of TOAC-related publications suggests that this unnatural amino acid will find increasing applications in the future.
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Grubišić S, Brancato G, Pedone A, Barone V. Extension of the AMBER force field to cyclic α,α dialkylated peptides. Phys Chem Chem Phys 2012; 14:15308-20. [DOI: 10.1039/c2cp42713c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Vieira RFF, Casallanovo F, Marín N, Paiva ACM, Schreier S, Nakaie CR. Conformational properties of angiotensin II and its active and inactive TOAC-labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies. Biopolymers 2009; 92:525-37. [DOI: 10.1002/bip.21295] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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