Species-specific thiol-disulfide equilibrium constants of ovothiol A and penicillamine with glutathione

RSC Advances ◽  
2016 ◽  
Vol 6 (32) ◽  
pp. 26757-26764 ◽  
Author(s):  
Arash Mirzahosseini ◽  
Béla Noszál
Keyword(s):  
Equilibrium Constants ◽  
Protonation Constants ◽  
Glutathione System ◽  
Redox Equilibrium ◽  
System P ◽  
The Difference ◽  
Species Specific

The correlation between species-specific redox equilibrium constants and the difference of thiolate protonation constants was determined for the ovothiol–glutathione system.

scholarly journals Species-Specific, pH-Independent, Standard Redox Potential of Selenocysteine and Selenocysteamine

Antioxidants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 465
Author(s):  
Tamás Pálla ◽  
Arash Mirzahosseini ◽  
Béla Noszál
Keyword(s):  
Redox Potential ◽  
Equilibrium Constants ◽  
Biological Significance ◽  
Redox Potentials ◽  
Acid Base ◽  
Redox Equilibrium ◽  
Standard Redox Potential ◽  
Ph Dependent ◽  
Species Specific ◽  
Redox Equilibria

Microscopic redox equilibrium constants and standard redox potential values were determined to quantify selenolate-diselenide equilibria of biological significance. The highly composite, codependent acid-base and redox equilibria of selenolates could so far be converted into pH-dependent, apparent parameters (equilibrium constants, redox potentials) only. In this work, the selenolate-diselenide redox equilibria of selenocysteamine and selenocysteine against dithiothreitol were analyzed by quantitative nuclear magnetic resonance (NMR) methods to characterize the interfering acid-base and redox equilibria. The directly obtained, pH-dependent, conditional redox equilibrium constants were then decomposed by our method into pH-independent, microscopic constants, which characterize the two-electron redox transitions of selenocysteamine and selenocysteine. The 12 different, species-specific parameter values show close correlation with the respective selenolate basicities, providing a tool to estimate otherwise inaccessible site-specific selenolate-diselenide redox potentials of related moieties in large peptides and proteins.

Photoisomerization-induced patterning of ion-pairing materials based on anionic azobenzene and its complex with a fluorescent π-electronic system

2021 ◽  
Vol 57 (35) ◽  
pp. 4287-4290
Author(s):  
Ryohei Yamakado ◽  
Issei Kitamura ◽  
Mitsuo Hara ◽  
Shusaku Nagano ◽  
Takahiro Seki ◽  
...  
Keyword(s):  
Surface Tension ◽  
Mass Transport ◽  
Trace Amount ◽  
Ion Pairs ◽  
Ion Pairing ◽  
Electronic System ◽  
Large Mass ◽  
System P ◽  
The Difference

Large mass transport driven by the difference in the photoisomerization-induced surface tension was demonstrated in ion pairs, enabling fluorescence patterning using a trace amount of photoisomerized anions in complexation with a π-electronic system.

scholarly journals The fundamental flaw of the HSAB principle is revealed by a complete speciation analysis of the [PtCl6−nBrn]2−(n = 0–6) system

2015 ◽  
Vol 17 (8) ◽  
pp. 5712-5724 ◽  
Author(s):  
W. J. Gerber ◽  
P.-H. van Wyk ◽  
D. M. E. van Niekerk ◽  
K. R. Koch
Keyword(s):  
Exchange Reaction ◽  
Ligand Exchange ◽  
Equilibrium Constants ◽  
Reaction Network ◽  
Speciation Analysis ◽  
Hsab Principle ◽  
Speciation Diagram ◽  
System P

Bjerrum's model of step-wise ligand exchange is extended to compute a complete speciation diagram for the [PtCl6−nBrn]2−(n= 0–6) system including all 17 equilibrium constants concerning the PtIVchlorido–bromido exchange reaction network (HERN).

scholarly journals Ba incorporation in benthic foraminifera

2017 ◽  
Author(s):  
Lennart J. de Nooijer ◽  
Anieke Brombacher ◽  
Antje Mewes ◽  
Gerald Langer ◽  
Gernot Nehrke ◽  
...  
Keyword(s):  
Trace Elements ◽  
Benthic Foraminifera ◽  
General Trend ◽  
Seawater Chemistry ◽  
Minor And Trace Elements ◽  
Foraminiferal Species ◽  
Element Partitioning ◽  
The Difference ◽  
Species Specific ◽  
New Applications

Abstract. Barium (Ba) incorporated in the calcite of many foraminiferal species is proportional to the concentration of Ba in seawater. Since the open ocean concentration of Ba closely follows seawater alkalinity, foraminiferal Ba/Ca can be used to reconstruct the latter. Alternatively, Ba/Ca from foraminiferal shells can also be used to reconstruct salinity in coastal settings where seawater Ba concentration corresponds to salinity as rivers contain much more Ba than seawater. Incorporation of a number of minor and trace elements is known to vary (greatly) between foraminiferal species and application of element/Ca ratios thus requires the use of species-specific calibrations. Here we show that calcite Ba/Ca correlates positively and linearly with seawater Ba/Ca in cultured specimens of two species of benthic foraminifera, Heterostegina depressa and Amphistegina lessonii. The slopes of the regression, however, vary 2–3 fold between these two species (0.33 and 0.78, respectively). This difference in Ba-partitioning resembles the difference in partitioning of other elements (Mg, Sr, B, Li and Na) in these foraminiferal taxa. A general trend across element partitioning for different species is described, which may help developing new applications of trace elements in foraminiferal calcite in reconstructing past seawater chemistry.

Influence of Freshwater Migration on the Reproductive Patterns of Anadromous Populations of Cisco (Coregonus artedii) and Lake Whitefish (C. clupeaformis)

1990 ◽  
Vol 47 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Yvan Lambert ◽  
Julian J. Dodson
Keyword(s):  
Adult Mortality ◽  
Lake Whitefish ◽  
Age At Maturity ◽  
Predominant Role ◽  
Reproductive Patterns ◽  
Interspecific Differences ◽  
Survival And Reproduction ◽  
Coregonus Artedii ◽  
The Difference ◽  
Species Specific

We tested the hypothesis that differences in the cost of freshwater migration are responsible for the different reproductive patterns exhibited by the Eastmain River (James Bay) populations of anadromous cisco and lake whitefish, as predicted by species-specific migration costs that result in interspecific differences in energy allocation to growth, survival, and reproduction. In the Eastmain River, cisco spawn at a younger age and a smaller size, have a shorter life span and show a higher fecundity and a higher mortality than lake whitefish. Assuming that the two populations are stable (being only lightly exploited), the two species spawn at an age that maximizes their lifetime fecundity. Either juvenile (between three and age at maturity) and/or adult mortality is of major importance in moulding the observed age at maturity but adult mortality may play a predominant role. Adult mortality is associated with migration, an obligatory cost representing a major proportion of the energy loss experienced by reproductive individuals. The difference in the energy cost of migration between the two species suggests that migration may play a predominant role in producing the different reproductive patterns of cisco and lake whitefish in the Eastmain River and that within the physiological and size constraints of each species, these patterns represent optimal adaptations maximizing fitness.

Variations on a segmental theme: muscle receptor organs and extensor neuromusculature in the squat lobster Munida quadrispina (Anomura, Galatheidae)

1995 ◽  
Vol 198 (12) ◽  
pp. 2453-2463 ◽  
Author(s):  
E Wallis ◽  
D Paul ◽  
B Antonsen ◽  
R Hollenberg
Keyword(s):  
Relative Size ◽  
Extracellular Recording ◽  
Blue Staining ◽  
Squat Lobster ◽  
Muscle Receptor ◽  
Axial Muscles ◽  
Extensor Motoneurones ◽  
The Difference ◽  
Segmental Variation ◽  
Species Specific

Extensor neuromusculature and the muscle receptor organs (MROs) associated with them have been conserved during the evolution of malacostracan crustaceans, despite species-specific differences between homologous segments in divergent taxa. Investigations of these differences could provide insight into how sensory and neuromuscular elements are modified to accommodate changing behavioural patterns. The most obvious differences between squat lobsters (galatheid anomurans) and macruran decapods, such as crayfish, are the greater dorso-ventral flattening of the galatheid abdomen and its flexed resting posture. To investigate whether the evolution of this altered posture affected extensor neuromusculature and MRO morphology and physiology, we used Methylene Blue staining, cobalt backfilling and extracellular recording techniques to describe these elements in the caudal thoracic and six abdominal segments of the squat lobster Munida quadrispina and compared our results with published descriptions of homologous elements in macrurans. In M. quadrispina, there is segmental variation both in the orientation of the MROs along the abdomen and in their physiological responses to stretch: apparent sensitivity is higher in caudal than rostral MROs. Homologues of three of the four accessory neurones found in crayfish occur, but AN#1 has a major dendrite not present in crayfish. Intersegmental differences in size and morphology of extensor motoneurones occur in M. quadrispina, as have been reported in crayfish, but are dissimilar in the two: abdominal ganglion 5 extensor motoneurones are the largest in M. quadrispina and the smallest in crayfish; this difference correlates with the difference in relative size of axial muscles along the abdomen reported previously for these species. M. quadrispina also differs from macrurans in having a single tonic, and no phasic, MRO on each side of the last abdominal segment. Together, these observations suggest that galatheids have evolved modified or additional neurobehavioural control(s) for the abdomen and tailfan.

BIOSYSTEMATICS OF THE GENUS EUXOA (LEPIDOPTERA: NOCTUIDAE). XVIH. COMPARATIVE BIOLOGY AND EXPERIMENTAL TAXONOMY OF THE SIBLING SPECIES EUXOA RIDMGSIANA (GRT.) AND EUXOA MAIMES (SM.)

1985 ◽  
Vol 117 (4) ◽  
pp. 481-493 ◽  
Author(s):  
J.R. Byers ◽  
D.L. Struble ◽  
J.D. Lafontaine
Keyword(s):  
Life Cycle ◽  
Reproductive Isolation ◽  
Sibling Species ◽  
Mate Recognition ◽  
Recognition System ◽  
Flight Period ◽  
Interspecific Differences ◽  
Mate Recognition System ◽  
The Difference ◽  
Species Specific

AbstractThe species previously recognized as Euxoa ridingsiana (Grt.) is shown to be composed of a sympatric pair of sibling species, Euxoa ridingsiana (Grt.) and Euxoa maimes (Sm.), which in the laboratory will produce viable F1 hybrids but no F2. Results of F1 sib and backcrosses show that the F1 males are fertile and the F1 females are infertile. In mating-bias tests conducted in laboratory cages, 74% of matings were conspecific and 26% interspecific. Differences in the diel periodicities of mating, which are about 2 h out of phase, may account for the mating bias. The duration of development of E. ridingsiana in the laboratory and its seasonal flight period in the field are about 2 weeks in advance of that of E. maimes. However, there is considerable overlap of the flight periods and, with the tendency of females of both species to mate several times, it is unlikely that the difference in seasonal emergence is enough to effect reproductive isolation. It is evident that, under natural conditions, reproductive isolation can be maintained entirely by species-specific sex pheromones. This mechanism of reproductive isolation is, however, apparently ineffective when moths are confined in cages in the laboratory.Biogeographic considerations suggest that the differences in life-cycle timing and mating periodicities might have been adaptations to adjust development and reproduction to prevailing ancestral environments. If the initial differentiation of the 2 species occurred in isolation and included at least an incipient shift in the pheromonal mate-recognition system, it is possible that upon reestablishment of contact between ancestral populations the differences in life-cycle timing and mating periodicities acting in concert could have effected substantial, albeit incomplete, reproductive isolation. Subsequent selection to reinforce assortative mating to preserve coadapted gene complexes could then have resulted in differentiation of discrete pheromonal systems and attainment of species status.

METHYL ACTIVATION AND sRNA METHYLATION BY SOLUBLE FRACTIONS OF SEVERAL VERTEBRATE LIVERS

1967 ◽  
Vol 45 (10) ◽  
pp. 1513-1522 ◽  
Author(s):  
R. L. Hancock
Keyword(s):  
Mouse Liver ◽  
Specific Interaction ◽  
Adult Rabbit ◽  
X Chromosomes ◽  
E Coli ◽  
Lower Vertebrates ◽  
The Difference ◽  
Species Specific ◽  
Methylase Activity

The amount of liver ATP: L-methionine S-adenosyltransferase activity varies widely in vertebrates from trace amounts in certain lower vertebrates, e.g. shark or turtle, to relatively large quantities in mammals, e.g. mouse or rabbit. The liver from male mice of a particular stock had only two-thirds the activity of female mouse liver. This difference is not explained by the difference between the sexes in number of X-chromosomes, since female mice with only one X-chromosome (X/0) had the same levels of liver S-adenosyltransferase activity as normal females with two X-chromosomes.sRNA methylase activity from mouse, shark, and rabbit liver supernatant fractions were studied with mouse, shark, and Escherichia coli sRNA. Highspeed supernatant fractions from both rabbit embryonic liver and mouse hepatoma hypermethylated E. coli sRNA which had been previously methylated by adult rabbit or mouse liver supernatant fractions. Hepatoma methylase(s) acts in an analogous manner to that of a species-specific interaction with heterologous and homologous sRNA.A calculation is made comparing the amount of sRNA methylase activity detected in vitro with mouse liver sRNA, with one which is theoretically derived; similar values are obtained. The variation found in vertebrate liver with respect to methyl activation and sRNA methylation is discussed.

scholarly journals Evaluation of User Behavior and Acceptance of an On-Bike System

2019 ◽  
Author(s):  
Gabriele Prati ◽  
Víctor Marín Puchades ◽  
Marco De Angelis ◽  
Luca Pietrantoni ◽  
Federico Fraboni ◽  
...  
Keyword(s):  
Field Study ◽  
User Behavior ◽  
Negative Emotions ◽  
Bicycle Safety ◽  
The Third ◽  
Warning Message ◽  
System P ◽  
The Difference ◽  
Motorized Vehicles

In this study, users’ acceptance of an on-bike system that warns about potential collisions with motorized vehicles as well as its influence on cyclists’ behavior was evaluated. Twenty-five participants took part in a field study that consisted of three different experimental tasks. All participants also completed a follow-up questionnaire at the completion of the three-task series to elicit information about the acceptance of the on-bike system. In the experiment phase, participants were asked to ride the bicycle throughout a circuit and to interact with a car at an intersection. Participants completed three laps of the circuit. The first lap involved no interaction with the car and served the purpose of habituation. In the second and third laps participants experienced a conflict with an incoming car at an intersection. In the second lap, the on-bike device was not activated, while in the third lap, participants received a warning message signaling the imminent conflict with the car. We compared the difference in user’s behavior between the second lap (conflict with a car without the warning of the on-bike system) and the third lap (conflict with a car with the warning of the on-bike system). Results showed that, when entering the crossroad, participants were more likely to decrease their speed in case of warning of the on-bike system. Further, the on-bike system was relatively well accepted by the participants. In particular, participants did not report negative emotions when using the system, while they trusted it and believed that using such technology would be free from effort. Participants were willing to spend on average 57.83€ for the system. This study highlights the potential of the on-bike system for promoting bicycle safety.

scholarly journals Theoretical study of dimethylcarbonate production by urea alcoholysis

2020 ◽  
Vol 62 (4) ◽  
pp. 38-50
Author(s):  
Nikita I. Kurshev ◽  
Keyword(s):  
Zinc Oxide ◽  
Density Functional ◽  
Dimethyl Carbonate ◽  
Activation Barrier ◽  
Equilibrium Constants ◽  
Density Functional Method ◽  
Intermediate Formation ◽  
Functional Method ◽  
Activation Barriers ◽  
The Difference

Using the density functional method М06, the mechanisms of non-catalytic reactions of transesterification of urea with methanol with the formation of dimethyl carbonate, as well as in catalysis with zinc oxide and acetate, were studied. The transesterification proceeds stepwise with the intermediate formation of methyl carbamate. The non-catalytic process of transesterification of urea with methanol proceeds by the mechanism of nucleophilic SN2 substitution and is accompanied by the formation of pre-reaction complexes, which through synchronous transition states turn into post-reaction complexes, decomposing into ammonia and methyl carbamate in the first stage and dimethyl carbonate in the second. It has been established that methanol associates can take part in these reactions. Their participation is preferable both kinetically and thermodynamically. An analysis of the equilibrium constants of the reaction of urea with methanol at various temperatures showed that in a wide temperature range their values remain large in the first stage – the formation of methyl carbamate and become significantly reversible in the second – the conversion of methyl carbamate to dimethyl carbonate. Reactions involving acetate and zinc oxide proceed through the same stages as non-catalytic interactions. In the case of zinc acetate catalyzed reactions, if methanol monomer is involved in the reaction, the reaction of formation of methyl carbamate has a lower activation barrier compared to the reaction of conversion of methyl carbamate to dimethyl carbonate. If a methanol dimer is involved in the reaction, both reactions have a practically equal activation barrier. In the case of zinc oxide catalyzed interactions, reactions involving a methanol dimer were not detected. The participation of the catalyst leads to a significant decrease in activation barriers, and a more significant decrease occurs in the case of catalysis with zinc oxide. The reason for the different catalytic activity, in our opinion, is the difference in the charges on the urea carbon atom in the pre-reaction complexes.

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