scholarly journals Absorption and Emission Spectroscopic Investigation of the Thermal Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor Archon2

2020 ◽  
Vol 21 (18) ◽  
pp. 6576
Author(s):  
Alfons Penzkofer ◽  
Arita Silapetere ◽  
Peter Hegemann
Keyword(s):  
Schiff Base ◽  
Melting Temperature ◽  
Absorption Maximum ◽  
Room Temperature ◽  
Voltage Sensor ◽  
Quantum Yields ◽  
Excitation Spectra ◽  
Thermal Dynamics ◽  
Absorption And Emission ◽  
Refrigerator Temperature

Archon2 is a fluorescent voltage sensor derived from Archaerhodopsin 3 (Arch) of Halorubrum sodomense using robotic multidimensional directed evolution approach. Here we report absorption and emission spectroscopic studies of Archon2 in Tris buffer at pH 8. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence excitation spectra were determined. The thermal stability of Archon2 was studied by long-time attenuation coefficient measurements at room temperature (21 ± 1 °C) and at refrigerator temperature (3 ± 1 °C). The apparent melting temperature was determined by stepwise sample heating up and cooling down (obtained apparent melting temperature: 63 ± 3 °C). In the protein melting process protonated retinal Schiff base (PRSB) with absorption maximum at 586 nm converted to de-protonated retinal Schiff base (RSB) with absorption maximum at 380 nm. Storage of Archon2 at room temperature and refrigerator temperature caused absorption coefficient decrease because of partial protein clustering to aggregates at condensation nuclei and sedimentation. At room temperature an onset of light scattering was observed after two days because of the beginning of protein unfolding. During the period of observation (18 days at 21 °C, 22 days at 3 °C) no change of retinal isomer composition was observed indicating a high potential energy barrier of S0 ground-state isomerization.

scholarly journals Absorption and Emission Spectroscopic Investigation of the Thermal Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor QuasAr1

2019 ◽  
Vol 20 (17) ◽  
pp. 4086 ◽  
Author(s):  
Penzkofer ◽  
Silapetere ◽  
Hegemann
Keyword(s):  
Schiff Base ◽  
Melting Temperature ◽  
Absorption Maximum ◽  
Voltage Sensor ◽  
Quantum Yields ◽  
Excitation Spectra ◽  
Thermal Dynamics ◽  
Absorption And Emission ◽  
Absorption Increase ◽  
Long Time

QuasAr1 is a fluorescent voltage sensor derived from Archaerhodopsin 3 (Arch) of Halorubrum sodomense by directed evolution. Here we report absorption and emission spectroscopic studies of QuasAr1 in Tris buffer at pH 8. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence excitation spectra were determined. The thermal stability of QuasAr1 was studied by long-time attenuation coefficient measurements at room temperature (23 ± 2 °C) and at 2.5 ± 0.5 °C. The apparent melting temperature was determined by stepwise sample heating up and cooling down (obtained apparent melting temperature: 65 ± 3 °C). In the protein melting process the originally present protonated retinal Schiff base (PRSB) with absorption maximum at 580 nm converted to de-protonated retinal Schiff base (RSB) with absorption maximum at 380 nm. Long-time storage of QuasAr1 at temperatures around 2.5 °C and around 23 °C caused gradual protonated retinal Schiff base isomer changes to other isomer conformations, de-protonation to retinal Schiff base isomers, and apoprotein structure changes showing up in ultraviolet absorption increase. Reaction coordinate schemes are presented for the thermal protonated retinal Schiff base isomerizations and deprotonations in parallel with the dynamic apoprotein restructurings.

scholarly journals Photocycle Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor QuasAr1

2019 ◽  
Vol 21 (1) ◽  
pp. 160
Author(s):  
Alfons Penzkofer ◽  
Arita Silapetere ◽  
Peter Hegemann
Keyword(s):  
Schiff Base ◽  
Quantum Yield ◽  
Absorption Band ◽  
Absorption Spectra ◽  
Absorption Maximum ◽  
Light Exposure ◽  
Voltage Sensor ◽  
Proton Release ◽  
Protonation State ◽  
State Changes

The retinal photocycle dynamics of the fluorescent voltage sensor QuasAr1 (Archaerhodopsin 3 P60S-T80S-D95H-D106H-F161V mutant from Halorubrum sodomense) in pH 8 Tris buffer was studied. The samples were photoexcited to the first absorption band of the protonated retinal Schiff base (PRSB) Ret_580 (absorption maximum at λmax ≈ 580 nm), and the retinal Schiff base photoisomerization and protonation state changes were followed by absorption spectra recordings during light exposure and after light exposure. Ret_580 turned out to be composed of two protonated retinal Schiff base isomers, namely Ret_580I and Ret_580II. Photoexcitation of Ret_580I resulted in barrier-involved isomerization to Ret_540 (quantum yield ≈ 0.056) and subsequent retinal proton release leading to Ret_410 deprotonated retinal Schiff base (RSB). In the dark, Ret_410 partially recovered to Ret_580I and partially stabilized to irreversible Ret_400 due to apoprotein restructuring (Ret_410 lifetime ≈ 2 h). Photoexcitation of Ret_580II resulted in barrier-involved isomerization to Ret_640 (quantum yield ≈ 0.00135) and subsequent deprotonation to Ret_370 (RSB). In the dark, Ret_370 partially recovered to Ret_580II and partially stabilized to irreversible Ret_350 due to apoprotein restructuring (Ret_370 lifetime ≈ 10 h). Photocycle schemes and reaction coordinate diagrams for Ret_580I and Ret_580II were developed and photocyle parameters were determined.

Decay dynamics of aromatic thione triplet states in fluid solution

1983 ◽  
Vol 61 (5) ◽  
pp. 894-900 ◽  
Author(s):  
A. Safarzadeh-Amiri ◽  
R. E. Verrall ◽  
R. P. Steer
Keyword(s):  
Room Temperature ◽  
Radiative Decay ◽  
Quantum Yields ◽  
Triplet States ◽  
Fluid Solution ◽  
Excitation Spectra ◽  
Decay Constants ◽  
Diffusion Controlled ◽  
Phosphorescence Emission ◽  
Group Rotation

Phosphorescence emission and excitation spectra, quantum yields, and lifetimes of several aromatic thiones have been measured in fluid solution at room temperature. Excitation to any of the excited electronic states accessible in the near-uv and visible regions of the spectrum results in population of the lowest triplet state with near unit quantum yield. Triplets of relatively inflexible thiones decay non-radiatively with rate constants of the order of 105 s−1 whereas thiones capable of higher amplitude flexion or group rotation exhibit non-radiative decay constants ≥ 107 s−1 at infinite dilution in aprotic solvents. Self-quenching occurs at diffusion-controlled rates.

Synthesis, structural characterization and catalytic activity of chlororuthenium(II) complexes with substituted Schiff base/phosphine ancillary ligands

2020 ◽  
Vol 75 (9-10) ◽  
pp. 851-857
Author(s):  
Chong Chen ◽  
Fule Wu ◽  
Jiao Ji ◽  
Ai-Quan Jia ◽  
Qian-Feng Zhang
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Structural Characterization ◽  
Room Temperature ◽  
Molecular Structures ◽  
Cationic Complex ◽  
Neutral Complex ◽  
Ancillary Ligands ◽  
X Ray ◽  
X Ray Crystallography

AbstractTreatment of [(η6-p-cymene)RuCl2]2 with one equivalent of chlorodiphenylphosphine in tetrahydrofuran at reflux afforded a neutral complex [(η6-p-cymene)RuCl2(κ1-P-PPh2OH)] (1). Similarly, the reaction of [Ru(bpy)2Cl2·2H2O] (bpy = 2,2′-bipyridine) and chlorodiphenylphosphine in methanol gave a cationic complex [Ru(bpy)2Cl(κ1-P-PPh2OCH3)](PF6) (2), while treatment of [RuCl2(PPh3)3] with [2-(C5H4N)CH=N(CH2)2N(CH3)2] (L1) in tetrahydrofuran at room temperature afforded a ruthenium(II) complex [Ru(PPh3)Cl2(κ3-N,N,N-L1)] (3). Interaction of the chloro-bridged complex [Ru(CO)2Cl2]n with one equivalent of [Ph2P(o-C6H4)CH=N(CH2)2N(CH3)2] (L2) led to the isolation of [Ru(CO)Cl2(κ3-P,N,N-L2)] (4). The molecular structures of the ruthenium(II) complexes 1–4 have been determined by single-crystal X-ray crystallography. The properties of the ruthenium(II) complex 4 as a hydrogenation catalyst for acetophenone were also tested.

scholarly journals The behaviour of visual purple at low temperature

1941 ◽  
Vol 179 (977) ◽  
pp. 151-159 ◽  
Keyword(s):  
Aqueous Solution ◽  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Absorption Curve ◽  
Quantum Yields

Visual purple is soluble and stable in a mixture of glycerol and water (3:1). At room temperature the spectrum of such a solution is identical with that of the aqueous solution. At — 73° C the peak of the absorption curve is higher and narrower than at room temperature, and it is shifted towards longer waves. The product of photodecomposition at — 73° C has a spectrum in ­ dependent of pH and is at low temperatures thermostable and photostable, but at room temperature it decomposes therm ally to indicator yellow. The primary product appears to be identical with transient orange. The quantum yields of the photoreaction at low and at room temperature are of the same order.

scholarly journals Regioisomeric Effect on the Excited-State Fate Leading to Room-Temperature Phosphorescence or Thermally Activated Delayed Fluorescence in a Dibenzophenazine-Cored Donor–Acceptor–Donor System

2021 ◽  
Author(s):  
Takumi Hosono ◽  
Nicolas Oliveira Decarli ◽  
Paola Zimmermann Crocomo ◽  
Tsuyoshi Goya ◽  
Leonardo Evaristo de Sousa ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Room Temperature Phosphorescence ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Donor Acceptor ◽  
Emission Behavior

Exploring design principle for switching thermally activated dealyed fluorescecne (TADF) and room temperature phosphorescence (RTP) is a fundamentally imporant research in developing triplet-mediated photofunctional organic materials. Herein systematic studies on the regioisomeric and substituents effects in a twisted donor–acceptor–donor (D–A–D) scaffold (A = dibenzo[a,j]phenazine; D = dihydrophenazasiline) on the fate of the excited state have been performed. The study revealed that the regiosiomerism clearly affects the emission behavior of the D–A–D compounds. Distinct difference in TADF, dual TADF & RTP, and dual RTP were observed, depending on the host used. Furthermore, OLED organic light-emitting diodes (OLEDs) fabricated with the developed emitters achieved high external quantum yields for RTP-based OLEDS up to 7.4%.

scholarly journals Producing Drink like Grafted Milk from Chickpeas and Evaluation of its Qualitative Properties

2020 ◽  
Vol 10 (03) ◽  
pp. 374-377
Author(s):  
Ibtihal Ismail Muhammad Al-Ani
Keyword(s):  
Room Temperature ◽  
Extraction Efficiency ◽  
Ph Value ◽  
Bacterial Number ◽  
Qualitative Properties ◽  
Product Density ◽  
Ph Values ◽  
Extraction Volume ◽  
Refrigerator Temperature ◽  
Soda Solution

The present study aimed to study the possibility of producing a drink that looks like grafted milk by using chickpeas and evaluate its physical, chemical, microbial, and sensory properties. The result showed the superiority of F treatment (soaking 100 grams of chickpeas at the refrigerator temperature 4ºC for 12 hours) over the rest seven treatments in extraction efficiency, which was 70%, while, it was 50.5% in H treatment (soaking 100 grams of chickpeas in the heated water at 60ºC for 30 minutes). The highest value of the product density was after water and flavorings addition in the D treatment (soaking 100 grams chickpeas in 0.05 soda solution at 60ºC for 30 minutes), and it was 0.97 g cm-3, compared with the lowest density 0.57 g cm-3 in A treatment (soaking 100 grams chickpeas in 0.05 soda solution at room temperature 25ºC for 12 hours). pH values were highest in A treatment compared with the other treatments, and its value was 7.66 in the 1st and 2nd day, after dissolving in a refrigerator at 4ºC, and then, for 5 minutes at room temperature 30ºC. The lowest value in the D treatment was 6.45 on the 1st day, and 6.87 on the 2nd day in the G treatment. On the 3rd day, the highest pH value was 7.13 in the D treatment, and the lowest value 6.79 was in the E treatment. pH highest value was 6.2 on the 4th day in A treatment. From the last results, it may be concluded that F treatment was the best in extraction efficiency, the final product density, and less total bacterial number, after dissolving for 5 days at refrigerator temperature 4ºC, and then, at room temperature 30ºC for 3 and 48 hours incubation. The best extraction volume and pH were in A treatment.

scholarly journals TOTAL Escherichia coli PADA SOSIS IKAN YANG DI-COATING DENGAN MIOFIBRIL ASAP CAIR SELAMA PENYIMPANAN

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Jupni Keno ◽  
Henny Adeleida Dien ◽  
Agnes Triasih Agustin
Keyword(s):  
Escherichia Coli ◽  
Nutritional Value ◽  
Room Temperature ◽  
Total Coliform ◽  
Fish Protein ◽  
Gram Negative ◽  
E Coli ◽  
Liquid Smoke ◽  
Refrigerator Temperature ◽  
Descriptive Method

Fish sausages are prepared foods that have a high nutritional value, but that is the weakness of this commodity is rapidly decaying nature. Bacterial pathogens that must be avoided include Escherichia coli. These bacteria are gram-negative, rod-shaped and motile spores are not. The purpose of this study is to calculate the total coliforms and E. coli in fish sausage coating of fish protein myofibrils Black Marlin (Makaira indica) during storage at room temperature (28–29°C), and refrigerator temperature (10–13°C). The method used is descriptive method, which is a study conducted to analyze an individual, the state, or the symptoms of a particular group. The results showed that the total coliform in fish sausage in coating with liquid smoke is stored at room temperature, the lowest value is 7 MPN/g, the highest of 120 MPN/g, while the lowest value refrigerator temperature is 7 MPN/g, the highest 93 MPN/g. Total coliform in fish sausage in smokeless liquid coating stored at room temperature with the lowest value is 7 MPN/g, the highest 210 MPN/g, while the lowest value refrigerator temperature is 7 MPN/g, and the highest is 120 MPN/g. Total coliform in fish sausages are not in the coating deposited at room temperature with the lowest value is 7 MPN/g, the highest of 240 MPN/g, at refrigerator temperature the lowest value is 7 MPN/g, and the highest is 150 MPN/g. Total E. coli showed that the fish sausage in coating with liquid smoke is stored at room temperature, the lowest value is 1 MPN/g, and the highest is 4 MPN/g, while the lowest value refrigerator temperature is <3 MPN/g, and The highest is 3 MPN/g. Total E. coli in fish sausage in smokeless coating liquid stored at room temperature, the lowest value is 2 MPN/g, and the highest is 4 MPN/g, while the temperature of the refrigerator lowest value is 1 MPN/g, and a high of 3 MPN/g. Total E. coli in sausages are not in the coating deposited at room temperature, the lowest value is 2 MPN/g, and the highest is 5 MPN/g, and the refrigerator temperature is the lowest rating 2 MPN/g, the highest is 4 MPN/g during storage .Keywords: fish sausage, coating, myofibril, Eschericia coli.  Sosis ikan merupakan makanan siap saji yang mempunyai nilai gizi tinggi, namun yang menjadi kelemahan dari komoniti ini adalah sifatnya yang cepat membusuk. Bakteri patogen yang harus dihindari antara lain Escherichia coli.  Bakteri ini bersifat gram negatif, berbentuk batang tidak spora dan bersifat motil. Tujuan penelitian ini yaitu untuk menghitung total koliform dan E. coli pada sosis ikan yang dicoating dari miofibril protein ikan Black Marlin (Makaira indica) selama penyimpanan suhu ruang (28–29°C), dan suhu kulkas (10–13°C). Metode penelitian yang digunakan adalah metode deskriptif, yaitu suatu penelitian yang dilakukan untuk menganalisa suatu individu, keadaan, gejala atau kelompok tertentu. Hasil penelitian menunjukkan bahwa total koliform pada sosis ikan yang dicoating dengan asap cair disimpan pada suhu ruang, nilai terendah yaitu 7 MPN/g, tertinggi 120 MPN/g, sedangkan pada suhu kulkas nilai yang terendah yaitu 7 MPN/g, tertinggi 93 MPN/g. Total koliform pada sosis ikan yang dicoating tanpa asap cair disimpan pada suhu ruang dengan nilai terendah yaitu 7 MPN/g, tertinggi 210 MPN/g, sedangkan pada suhu kulkas nilai yang terendah yaitu 7 MPN/g, dan tertinggi 120 MPN/g. Total koliform pada sosis ikan tidak dicoating disimpan pada suhu ruang dengan nilai terendah yaitu 7 MPN/g, tertinggi 240 MPN/g , pada suhu kulkas nilai terendah yaitu 7 MPN/g , dan tertinggi 150 MPN/g. Total E. coli menunjukkan bahwa pada sosis ikan yang dicoating dengan asap cair disimpan pada suhu ruang, yaitu nilai terendah 3 MPN/g, dan tertinggi 4 MPN/g, sedangkan pada suhu kulkas nilai terendah yaitu <3 MPN/g, dan tertinggi 3 MPN/g. Total E. coli pada sosis ikan yang dicoating tanpa asap cair disimpan pada suhu ruang, yaitu nilai terendah 3 MPN/g, dan tertinggi 4 MPN/g, sedangkan pada suhu kulkas nilai terendah yaitu <3 MPN/g , dan tertinggi 3 MPN/g. Total E. coli pada sosis tidak dicoatingdisimpan pada suhu ruang, yaitu nilai terendah 4 MPN/g, dan tertinggi 7 MPN/g, dan pada suhu kulkas yaitu nilai terendah 3 MPN/g, tertinggi 4 MPN/g selama penyimpanan.Kata kunci: sosis ikan, coating, myofibril, Eschericia coli.

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