scholarly journals Structure-function-dynamics relationships in the peculiar Planktothrix PCC7805 OCP1: impact of his-tagging and carotenoid type.

2022 ◽  
Author(s):  
Adjele Wilson ◽  
Elena A. Andreeva ◽  
Stanislaw Nizinski ◽  
Lea Talbot ◽  
Elisabeth Hartmann ◽  
...  
Keyword(s):  
Fluorescence Quenching ◽  
Structure Function ◽  
Excited States ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Thermal Recovery ◽  
Crystal Forms ◽  
His Tag ◽  
C Terminus ◽  
Orange Carotenoid Protein

The orange carotenoid protein (OCP) is a photoactive protein involved in cyanobacterial photoprotection. Here, we report on the functional, spectral and structural characteristics of the peculiar Planktothrix PCC7805 OCP (Plankto-OCP). We show that this OCP variant is characterized by higher photoactivation and recovery rates, and a stronger energy-quenching activity, compared to other OCPs studied thus far. We characterize the effect of the functionalizing carotenoid and of his-tagging on these reactions, and the time scales on which these modifications affect photoactivation. The presence of a His-tag at the C-terminus has a large influence on photoactivation, thermal recovery and PBS-fluorescence quenching, and likewise for the nature of the carotenoid that additionally affects the yield and characteristics of excited states and the ns-s dynamics of photoactivated OCP. By solving the structures of Plankto-OCP in the ECN- and CAN-functionalized states, each in two closely-related crystal forms, we further unveil the molecular breathing motions that animate Plankto-OCP at the monomer and dimer levels. We finally discuss the structural changes that could explain the peculiar properties of Plankto-OCP.

Solvent Dependence of Structural Dynamics and Spin-flip Processes in 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (ortho-3CzBN)

2020 ◽  
Author(s):  
Masaki Saigo ◽  
Kiyoshi Miyata ◽  
Hajime Nakanotani ◽  
Chihaya Adachi ◽  
Ken Onda
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Structural Changes ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Time Resolved ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Solvent Dependence ◽  
Acetonitrile Solutions

We have investigated the solvent-dependence of structural changes along with intersystem crossing of a thermally activated delayed fluorescence (TADF) molecule, 3,4,5-tri(9H-carbazole-9-yl)benzonitrile (o-3CzBN), in toluene, tetrahydrofuran, and acetonitrile solutions using time-resolved infrared (TR-IR) spectroscopy and DFT calculations. We found that the geometries of the S1 and T1 states are very similar in all solvents though the photophysical properties mostly depend on the solvent. In addition, the time-dependent DFT calculations based on these geometries suggested that the thermally activated delayed fluorescence process of o-3CzBN is governed more by the higher-lying excited states than by the structural changes in the excited states.<br>

An acidity scale, [H+]hv, for proton quenching of excited states

1989 ◽  
Vol 67 (2) ◽  
pp. 227-238 ◽  
Author(s):  
J. A. Pincock ◽  
P. R. Redden
Keyword(s):  
Excited State ◽  
Fluorescence Quenching ◽  
Excited States ◽  
Benzyl Alcohols ◽  
Fluorescent Indicator ◽  
Quenching Of Fluorescence ◽  
Acidity Scale

An acidity scale for excited state protonation kinetics in 20% ethanol:80% aqueous sulfuric has been developed using 1-cyano-naphthalene as a fluorescent indicator. The utility of this new scale is demonstrated using the proton quenching of fluorescence of a variety of chromophores. These include 1- and 2-cyanonaphthalenes, 1- and 2-methoxynaphthalenes, benzyl alcohols, toluenes, and 2-vinylnaphthalene. Keywords: acidity scale, fluorescence quenching, excited state basicity.

Study of Properties of Expanded Graphite – Polymer Porous Composite by Acoustic Emission Method

2013 ◽  
Vol 58 (4) ◽  
pp. 1331-1336 ◽  
Author(s):  
J. Berdowski ◽  
S. Berdowska ◽  
F. Aubry
Keyword(s):  
Acoustic Emission ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Physical And Mechanical Properties ◽  
Expanded Graphite ◽  
Composite Membranes ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Graphite Composite ◽  
Wide Range

Abstract The purpose of this paper was to investigate the physical and mechanical properties of compressed expanded graphite (CEG) and their porous derivatives after impregnation, polymerization; and carbonization by the use of acoustic emission method (AE). The mechanical and structural characteristics of compressed expanded graphite and their three groups of porous composites after each technological process are presented and discussed. The measurements of acoustic emission parameters in these materials were carried out at wide range of frequency of the waves (0.1÷2.5 MHz). The changes of two of parameters: - AE pulses counts rate and spectrum distribution of AE waves - are presented in this paper. The analysis of the respective parameters AE also gives possibility to determine the micro- and macro structural changes of materials at different levels of technological processes. Applications of these materials as catalysts with high specific surface make them very interesting subject of study. Also compressed expanded graphite composite membranes prepared from furfuryl alcohol polymers are promising for gas separation.

The structure and changes of China’s land system

2019 ◽  
Vol 11 (3) ◽  
pp. 471-488 ◽  
Author(s):  
Liu Shouying
Keyword(s):  
Economic Growth ◽  
Institutional Change ◽  
Structural Changes ◽  
Structural Characteristics ◽  
Institutional Arrangements ◽  
Reform Process ◽  
Content Type ◽  
The Past ◽  
Land System ◽  
Rapid Economic Growth

Purpose The purpose of this paper is to analyze the structure and changes of China’s land system. To achieve this aim, the paper is divided into four parts. The first part gives a brief introduction to the structural characteristics of the Chinese land institutional arrangements; the second part analyzes the reform process of the land system in the past 40 years and its path of change; the third part engages the discussion about the historic contribution made by the land institutional change to rapid economic growth and structural changes; and the final part is conclusion and some policy implications. Design/methodology/approach After 40 years of reforms and opening up, China has not only created a growth miracle unparalleled for any major country in human history, but also transformed itself from a rural to an urban society. Behind this great transformation is a systemic reform in land institutions. Rural land institutions went from collectively owned to household responsibility system, thereby protecting farmers’ land rights. This process resulted in long-term sustainable growth in China’s agriculture, a massive rural-urban migration and a historical agricultural transformation. The conversion of agricultural land to non-agricultural uses and the introduction of market mechanisms made land a policy tool in driving high economic growth, industrialization and urbanization. Findings Research shows that the role of land and its relationship with the economy will inevitably change as China’s economy enters a new stage of medium-to-high speed growth. With economic restructuring, low-cost industrial land will be less effective. Urbanization is also shifting from rapid expansion to endogenous growth so that returns on land capitalization will decrease and risks will increase. Therefore, China must abandon land-dependent growth model through deepening land reforms and adapt a new pattern of economic development. Originality/value This paper gives a brief introduction to the structural characteristics of the Chinese land institutional arrangements, analyzes the reform process of the land system in the past 40 years and its path of change, and evaluates the historic contribution made by the land institutional change to rapid economic growth and structural changes.

scholarly journals Arachidonic acid promotes the binding of 5-lipoxygenase on nanodiscs containing 5-lipoxygenase activating protein in the absence of calcium-ions

2020 ◽  
Author(s):  
Ramakrishnan B. Kumar ◽  
Pasi Purhonen ◽  
Hans Hebert ◽  
Caroline Jegerschöld
Keyword(s):  
Arachidonic Acid ◽  
Complex Formation ◽  
Calcium Ions ◽  
Dependent Manner ◽  
Present Communication ◽  
Nuclear Membranes ◽  
His Tag ◽  
C Terminus ◽  
Transmission Electron

AbstractAmong the first steps in inflammation is the conversion of arachidonic acid (AA) stored in the cell membranes into leukotrienes. This occurs mainly in leukocytes and depends on the interaction of two proteins: 5-lipoxygenase (5LO), stored away from the nuclear membranes until use and 5-lipoxygenase activating protein (FLAP), a transmembrane, homotrimeric protein, constitutively present in nuclear membrane. We could earlier visualize the binding of 5LO to nanodiscs in the presence of Ca2+-ions by the use of transmission electron microscopy (TEM) on samples negatively stained by sodium phosphotungstate. In the absence of Ca2+-ions 5LO did not bind to the membrane. In the present communication, FLAP reconstituted in the nanodiscs which could be purified if the His-tag was located on the FLAP C-terminus but not the N-terminus. Our aim was to find out if 1) 5LO would bind in a Ca2+-dependent manner also when FLAP is present? 2) Would the substrate (AA) have effects on 5LO binding to FLAP-nanodiscs? TEM was used to assess the complex formation between 5LO and FLAP-nanodiscs along with, sucrose gradient purification, gel-electrophoresis and mass spectroscopy. It was found that presence of AA by itself induces complex formation in the absence of added calcium. This finding corroborates that AA is necessary for the complex formation and that a Ca2+-flush is mainly needed for the recruitment of 5LO to the membrane. Our results also showed that the addition of Ca2+-ions promoted binding of 5LO on the FLAP-nanodiscs as was also the case for nanodiscs without FLAP incorporated. In the absence of added substances no 5LO-FLAP complex was formed. Another finding is that the formation of a 5LO-FLAP complex appears to induce fragmentation of 5LO in vitro.

scholarly journals Improved scFv Anti-LOX-1 Binding Activity by Fusion with LOX-1-Binding Peptides

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Wei Hu ◽  
Qiuhong Xie ◽  
Hongyu Xiang
Keyword(s):  
Targeted Delivery ◽  
Structural Characteristics ◽  
Low Density Lipoprotein ◽  
Three Dimensional ◽  
Density Lipoprotein ◽  
Binding Activity ◽  
Single Chain ◽  
C Terminus ◽  
Density Lipoprotein Receptor ◽  
Therapeutic Molecules

The oxidized low-density lipoprotein receptor-1 (LOX-1) targeted single-chain variable fragment (scFvs) is a promising molecule for the targeted delivery of imaging and therapeutic molecules of atherosclerotic diseases; however, its applications are limited by the inherent low antigen affinity. In this study, the three-dimensional (3D) model of the anti-LOX-1 scFv was constructed and its docking with the LOX-1 protein was developed. To improve the LOX-1-binding activity, the anti-LOX-1 scFv was designed to fuse with one of three LOX-1-binding heptapeptides, LTPATAI, FQTPPQL, and LSIPPKA, at its N-terminus and C-terminus and in the linker region, which have different LOX-1-binding interfaces with the anti-LOX-1 scFv analyzed by an array of computational approaches. These scFv/peptide fusions were constructed, successfully expressed in Brevibacillus choshinensis hosts, and purified by a two-step column purification process. The antigen binding activity, structural characteristics, thermal stability, and stability in serum of these fusion proteins were examined. Results showed that the scFv with N-terminal fusing peptides proteins demonstrated increased LOX-1-binding activity without decrease in stability. These findings will help increase the application efficacy of LOX-1 targeting scFv in LOX-1-based therapy.

Structure/function analysis of the C3a-receptor C-terminus

2000 ◽  
Vol 49 (1-2) ◽  
pp. 89
Author(s):  
B. Settmacher ◽  
C. Rheinheimer ◽  
M. Oppermann ◽  
H. Hamacher ◽  
D. Bock ◽  
...  
Keyword(s):  
Structure Function ◽  
Function Analysis ◽  
C Terminus

scholarly journals Investigation of the Structural Changes and Catalytic Properties of FeNi Nanostructures as a Result of Exposure to Gamma Radiation

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 254
Author(s):  
Daryn B. Borgekov ◽  
Maxim V. Zdorovets ◽  
Dmitriy I. Shlimas ◽  
Artem L. Kozlovskiy
Keyword(s):  
Gamma Radiation ◽  
Point Defects ◽  
Gamma Rays ◽  
Structural Changes ◽  
Catalytic Properties ◽  
Structural Characteristics ◽  
Catalytic Reactions ◽  
Radiation Doses ◽  
Crystallite Orientation ◽  
Complete Destruction

The paper presents the results of changes in the structural characteristics, and the degree of texturing of FeNi nanostructures close in composition to permalloy compounds as a result of directed modification by gamma radiation with an energy of 1.35 MeV and doses from 100 to 500 kGy. The choices of energy and radiation doses were due to the need to modify the structural properties, which consisted of annealing the point defects that occurred during the synthesis along the entire length of the nanotubes. The initial FeNi nanostructures were polycrystalline nanotubes of anisotropic crystallite orientation, obtained by electrochemical deposition. The study found that exposure to gamma rays led to fewer defects in the structure, and reorientation of crystallites, and at doses above 300 kGy, the presence of one selected texture direction (111) in the structure. During tests of the corrosion resistance of synthesized and modified nanostructures in a PBS solution at various temperatures, it was found that exposure to gamma rays led to a significant decrease in the rate of degradation of nanotubes and an increase in the potential life of up to 20 days. It was established that at the first stage of testing, the degradation of nanostructures is accompanied by the formation of oxide inclusions, which subsequently lead to the formation of pitting corrosion and subsequent partial or complete destruction of the nanostructures. It is shown that gamma radiation is promising not only for targeted modification of nanostructures and increasing resistance to degradation, but also for increasing the rate of catalytic reactions of the PNA-PPD type.

Structural variations in strained crystalline multilayers

1994 ◽  
Vol 9 (8) ◽  
pp. 2190-2197 ◽  
Author(s):  
J. Hoekstra ◽  
H. Yan ◽  
G. Kalonji ◽  
H. Jónsson
Keyword(s):  
Structural Changes ◽  
Elevated Temperatures ◽  
Lattice Mismatch ◽  
Structural Characteristics ◽  
Binding Energies ◽  
Structural Defects ◽  
Interatomic Potentials ◽  
Structural Variations ◽  
Common Neighbor ◽  
Hcp Structure

We present a computer simulation study of thin crystalline multilayers constructed from two fcc solids with differing lattice constants and binding energies. Initially the two solids have the same orientation, and the interface is perpendicular to the common [100] direction. We then minimize the energy of the system at zero temperature or equilibrate it at a finite temperature. Both materials are described by Lennard-Jones interatomic potentials. A novel technique for analyzing local atomic ordering, common neighbor analysis, is used to identify structural characteristics in these systems. As we gradually vary the lattice mismatch between the two solids, several structural changes are observed in the layers of smaller atoms after energy minimization. At a mismatch larger than 14%, the layers transform into the hep structure, while at smaller mismatches extended structural defects are generated. At elevated temperatures, the hcp structure is transformed back to fcc, and the structure defects disappear.

Sign in / Sign up

Export Citation Format

Share Document