Role of Chiral Configuration in the Photoinduced Interaction of D- and L-Tryptophan with Optical Isomers of Ketoprofen in Linked Systems

The study of the L- and D-amino acid properties in proteins and peptides has attracted considerable attention in recent years, as the replacement of even one L-amino acid by its D-analogue due to aging of the body is resulted in a number of pathological conditions, including Alzheimer’s and Parkinson’s diseases. A recent trend is using short model systems to study the peculiarities of proteins with D-amino acids. In this report, the comparison of the excited states quenching of L- and D-tryptophan (Trp) in a model donor–acceptor dyad with (R)- and (S)-ketoprofen (KP-Trp) was carried out by photochemically induced dynamic nuclear polarization (CIDNP) and fluorescence spectroscopy. Quenching of the Trp excited states, which occurs via two mechanisms: prevailing resonance energy transfer (RET) and electron transfer (ET), indeed demonstrates some peculiarities for all three studied configurations of the dyad: (R,S)-, (S,R)-, and (S,S)-. Thus, the ET efficiency is identical for (S,R)- and (R,S)-enantiomers, while RET differs by 1.6 times. For (S,S)-, the CIDNP coefficient is almost an order of magnitude greater than for (R,S)- and (S,R)-. To understand the source of this difference, hyperpolarization of (S,S)-and (R,S)- has been calculated using theory involving the electron dipole–dipole interaction in the secular equation.

Download Full-text

Calmodulin-dependent binding to the NHE1 cytosolic tail mediates activation of the Na+/H+ exchanger by Ca2+ and endothelin

AJP Cell Physiology ◽

10.1152/ajpcell.00208.2013 ◽

2013 ◽

Vol 305 (11) ◽

pp. C1161-C1169 ◽

Cited By ~ 10

Author(s):

Xiuju Li ◽

Daniel Prins ◽

Marek Michalak ◽

Larry Fliegel

Keyword(s):

Amino Acid ◽

Fluorescent Protein ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Time Dependent ◽

Wild Type ◽

Membrane Domain ◽

Plasma Membrane Protein ◽

Nhe1 Activity

The mammalian Na+/H+ exchanger isoform 1 (NHE1) is a ubiquitous plasma membrane protein that regulates intracellular pH by removing a single proton (H+) in exchange for one extracellular Na+. The human protein contains a ∼500-amino acid membrane domain and a regulatory, ∼315-amino acid cytosolic domain. NHE1 is activated by a number of hormones including endothelin (ET) and by Ca2+. The regulatory tail possesses an inhibitory calmodulin (CaM)-binding domain, and inhibition of NHE1 is relieved by binding of a Ca2+-CaM complex. We examined the dynamics of ET-1 and Ca2+ regulation of binding to NHE1 in vivo. CFP was linked to the NHE1 protein cytoplasmic COOH terminus. This was stably transfected into AP-1 cells that are devoid of their own NHE1 protein. The protein was expressed and targeted properly and retained NHE1 activity comparable to the wild-type protein. We examined the in vivo coupling of NHE1 to CaM by Förster resonance energy transfer using CaM linked to the fluorescent protein Venus. CaM interaction with NHE1 was dynamic. Removal of serum reduced CaM interaction with NHE1. Addition of the Ca2+ ionophore ionomycin increased the interaction between CaM and NHE1. We expressed an ET receptor in AP-1 cells and also found a time-dependent association of NHE1 with CaM in vivo that was dependent on ET treatment. The results are the first demonstration of the in vivo association of NHE1 and CaM through ET-dependent signaling pathways.

Download Full-text

The Interplay of the Unfolded Protein Response in Neurodegenerative Diseases: A Therapeutic Role of Curcumin

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.767493 ◽

2021 ◽

Vol 13 ◽

Author(s):

Sitabja Mukherjee ◽

Awdhesh Kumar Mishra ◽

G. D. Ghouse Peer ◽

Sali Abubaker Bagabir ◽

Shafiul Haque ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Neurodegenerative Diseases ◽

Unfolded Protein Response ◽

Neurodegenerative Disorders ◽

The Body ◽

Model Systems ◽

Unfolded Protein ◽

Body Tissues ◽

Parkinson’S Diseases ◽

Protein Response

Abnormal accumulation of misfolded proteins in the endoplasmic reticulum and their aggregation causes inflammation and endoplasmic reticulum stress. This promotes accumulation of toxic proteins in the body tissues especially brain leading to manifestation of neurodegenerative diseases. The studies suggest that deregulation of proteostasis, particularly aberrant unfolded protein response (UPR) signaling, may be a common morbific process in the development of neurodegeneration. Curcumin, the mixture of low molecular weight polyphenolic compounds from turmeric, Curcuma longa has shown promising response to prevents many diseases including current global severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and neurodegenerative disorders. The UPR which correlates positively with neurodegenerative disorders were found affected by curcumin. In this review, we examine the evidence from many model systems illustrating how curcumin interacts with UPR and slows down the development of various neurodegenerative disorders (ND), e.g., Alzheimer’s and Parkinson’s diseases. The recent global increase in ND patients indicates that researchers and practitioners will need to develop a new pharmacological drug or treatment to manage and cure these neurodegenerative diseases.

Download Full-text

Development of a Human Estrogen Receptor Dimerization Assay for the Estrogenic Endocrine-Disrupting Chemicals Using Bioluminescence Resonance Energy Transfer

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18168875 ◽

2021 ◽

Vol 18 (16) ◽

pp. 8875

Author(s):

Hye Mi Kim ◽

Hyeyeong Seo ◽

Yooheon Park ◽

Hee-Seok Lee ◽

Seok-Hee Lee ◽

...

Keyword(s):

Energy Transfer ◽

Binding Affinity ◽

Binding Assay ◽

Radioligand Binding ◽

Endocrine Disrupting Chemicals ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

The Body ◽

Bioluminescence Resonance Energy Transfer ◽

Endocrine Disrupting

Endocrine-disrupting chemicals (EDCs) are found in food and various other substances, including pesticides and plastics. EDCs are easily absorbed into the body and have the ability to mimic or block hormone function. The radioligand binding assay based on the estrogen receptors binding affinity is widely used to detect estrogenic EDCs but is limited to radioactive substances and requires specific conditions. As an alternative, we developed a human cell-based dimerization assay for detecting EDC-mediated ER-alpha (ERα) dimerization using bioluminescence resonance energy transfer (BRET). The resultant novel BRET-based on the ERα dimerization assay was used to identify the binding affinity of 17β-estradiol (E2), 17α-estradiol, corticosterone, diethylhexyl phthalate, bisphenol A, and 4-nonylphenol with ERα by measuring the corresponding BRET signals. Consequently, the BRET signals from five chemicals except corticosterone showed a dose-dependent sigmoidal curve for ERα, and these chemicals were suggested as positive chemicals for ERα. In contrast, corticosterone, which induced a BRET signal comparable to that of the vehicle control, was suggested as a negative chemical for ERα. Therefore, these results were consistent with the results of the existing binding assay for ERα and suggested that a novel BRET system can provide information about EDCs-mediated dimerization to ERα.

Download Full-text

Excitons in Carbonic Nanostructures

C – Journal of Carbon Research ◽

10.3390/c5040071 ◽

2019 ◽

Vol 5 (4) ◽

pp. 71 ◽

Cited By ~ 8

Author(s):

Alexander Demchenko

Keyword(s):

Excited States ◽

Quantum Coherence ◽

Inorganic Carbon ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Collective Excitations ◽

Electronic Systems ◽

Electronic Interactions ◽

Exciton Transport

Unexpectedly bright photoluminescence emission can be observed in materials incorporating inorganic carbon when their size is reduced from macro–micro to nano. At present, there is no consensus in its understanding, and many suggested explanations are not consistent with the broad range of experimental data. In this Review, I discuss the possible role of collective excitations (excitons) generated by resonance electronic interactions among the chromophore elements within these nanoparticles. The Förster-type resonance energy transfer (FRET) mechanism of energy migration within nanoparticles operates when the composing fluorophores are the localized electronic systems interacting at a distance. Meanwhile, the resonance interactions among closely located fluorophores may lead to delocalization of the excited states over many molecules resulting in Frenkel excitons. The H-aggregate-type quantum coherence originating from strong coupling among the transition dipoles of adjacent chromophores in a co-facial stacking arrangement and exciton transport to emissive traps are the basis of the presented model. It can explain most of the hitherto known experimental observations and must stimulate the progress towards their versatile applications.

Download Full-text

Efficient Synthesis and In Vivo Incorporation of Acridon-2-ylalanine, a Fluorescent Amino Acid for Lifetime and Förster Resonance Energy Transfer/Luminescence Resonance Energy Transfer Studies

Journal of the American Chemical Society ◽

10.1021/ja403247j ◽

2013 ◽

Vol 135 (50) ◽

pp. 18806-18814 ◽

Cited By ~ 53

Author(s):

Lee C. Speight ◽

Anand K. Muthusamy ◽

Jacob M. Goldberg ◽

John B. Warner ◽

Rebecca F. Wissner ◽

...

Keyword(s):

Energy Transfer ◽

Amino Acid ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Forster Resonance Energy Transfer ◽

Förster Resonance Energy Transfer ◽

Efficient Synthesis ◽

Fluorescent Amino Acid ◽

Förster Resonance

Download Full-text

Measuring distances between TRPV1 and the plasma membrane using a noncanonical amino acid and transition metal ion FRET

The Journal of General Physiology ◽

10.1085/jgp.201511531 ◽

2016 ◽

Vol 147 (2) ◽

pp. 201-216 ◽

Cited By ~ 31

Author(s):

William N. Zagotta ◽

Moshe T. Gordon ◽

Eric N. Senning ◽

Mika A. Munari ◽

Sharona E. Gordon

Keyword(s):

Plasma Membrane ◽

Energy Transfer ◽

Amino Acid ◽

Membrane Proteins ◽

Transition Metal ◽

Fluorescence Resonance Energy Transfer ◽

Metal Ion ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Noncanonical Amino Acid

Despite recent advances, the structure and dynamics of membrane proteins in cell membranes remain elusive. We implemented transition metal ion fluorescence resonance energy transfer (tmFRET) to measure distances between sites on the N-terminal ankyrin repeat domains (ARDs) of the pain-transducing ion channel TRPV1 and the intracellular surface of the plasma membrane. To preserve the native context, we used unroofed cells, and to specifically label sites in TRPV1, we incorporated a fluorescent, noncanonical amino acid, L-ANAP. A metal chelating lipid was used to decorate the plasma membrane with high-density/high-affinity metal-binding sites. The fluorescence resonance energy transfer (FRET) efficiencies between L-ANAP in TRPV1 and Co2+ bound to the plasma membrane were consistent with the arrangement of the ARDs in recent cryoelectron microscopy structures of TRPV1. No change in tmFRET was observed with the TRPV1 agonist capsaicin. These results demonstrate the power of tmFRET for measuring structure and rearrangements of membrane proteins relative to the cell membrane.

Download Full-text