Investigating the Activation Kinetics of Phosphoramidites for Oligonucleotide Synthesis

2021 ◽  
Author(s):  
Fiona J. Laraman ◽  
Heidi Fisk ◽  
David T. E. Whittaker ◽  
Janette H. Cherryman ◽  
Louis J. Diorazio
Keyword(s):  
Oligonucleotide Synthesis ◽  
Activation Kinetics ◽  
Kinetics Of

scholarly journals Mixing state and compositional effects on CCN activity and droplet growth kinetics of size-resolved CCN in an urban environment

2012 ◽  
Vol 12 (21) ◽  
pp. 10239-10255 ◽  
Author(s):  
L. T. Padró ◽  
R. H. Moore ◽  
X. Zhang ◽  
N. Rastogi ◽  
R. J. Weber ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Water Soluble ◽  
Anthropogenic Sources ◽  
Droplet Growth ◽  
Mixing State ◽  
Aerosol Composition ◽  
Activation Kinetics ◽  
Aerosol Mixing State ◽  
Kinetics Of ◽  
Ccn Activity

Abstract. Aerosol composition and mixing state near anthropogenic sources can be highly variable and can challenge predictions of cloud condensation nuclei (CCN). The impacts of chemical composition on CCN activation kinetics is also an important, but largely unknown, aspect of cloud droplet formation. Towards this, we present in-situ size-resolved CCN measurements carried out during the 2008 summertime August Mini Intensive Gas and Aerosol Study (AMIGAS) campaign in Atlanta, GA. Aerosol chemical composition was measured by two particle-into-liquid samplers measuring water-soluble inorganic ions and total water-soluble organic carbon. Size-resolved CCN data were collected using the Scanning Mobility CCN Analysis (SMCA) method and were used to obtain characteristic aerosol hygroscopicity distributions, whose breadth reflects the aerosol compositional variability and mixing state. Knowledge of aerosol mixing state is important for accurate predictions of CCN concentrations and that the influence of an externally-mixed, CCN-active aerosol fraction varies with size from 31% for particle diameters less than 40 nm to 93% for accumulation mode aerosol during the day. Assuming size-dependent aerosol mixing state and size-invariant chemical composition decreases the average CCN concentration overprediction (for all but one mixing state and chemical composition scenario considered) from over 190–240% to less than 20%. CCN activity is parameterized using a single hygroscopicity parameter, κ, which averages to 0.16 ± 0.07 for 80 nm particles and exhibits considerable variability (from 0.03 to 0.48) throughout the study period. Particles in the 60–100 nm range exhibited similar hygroscopicity, with a κ range for 60 nm between 0.06–0.076 (mean of 0.18 ± 0.09). Smaller particles (40 nm) had on average greater κ, with a range of 0.20–0.92 (mean of 0.3 ± 0.12). Analysis of the droplet activation kinetics of the aerosol sampled suggests that most of the CCN activate as rapidly as calibration aerosol, suggesting that aerosol composition exhibits a minor (if any) impact on CCN activation kinetics.

scholarly journals Activation Kinetics of AMPA Receptor Channels Reveal the Number of Functional Agonist Binding Sites

1998 ◽  
Vol 18 (1) ◽  
pp. 119-127 ◽  
Author(s):  
John D. Clements ◽  
Anne Feltz ◽  
Yoshinori Sahara ◽  
Gary L. Westbrook
Keyword(s):  
Ampa Receptor ◽  
Binding Sites ◽  
Agonist Binding ◽  
Activation Kinetics ◽  
Kinetics Of ◽  
Ampa Receptor Channels

scholarly journals Activation Kinetics of RAF Protein in the Ternary Complex of RAF, RAS-GTP, and Kinase on the Plasma Membrane of Living Cells

2011 ◽  
Vol 286 (42) ◽  
pp. 36460-36468 ◽  
Author(s):  
Kayo Hibino ◽  
Tatsuo Shibata ◽  
Toshio Yanagida ◽  
Yasushi Sako
Keyword(s):  
Plasma Membrane ◽  
Ternary Complex ◽  
Living Cells ◽  
Activation Kinetics ◽  
Kinetics Of

Kinetics of Ca2(+)-ATPase activation in platelet membranes of essential hypertensives and normotensives

1990 ◽  
Vol 258 (6) ◽  
pp. C988-C994 ◽  
Author(s):  
J. Takaya ◽  
N. Lasker ◽  
R. Bamforth ◽  
M. Gutkin ◽  
L. H. Byrd ◽  
...  
Keyword(s):  
Essential Hypertension ◽  
Family History ◽  
Positive Family History ◽  
Plasma Renin ◽  
Initial Reaction ◽  
Activation Kinetics ◽  
Negative Family History ◽  
History Of ◽  
Blacks And Whites ◽  
Kinetics Of

To explore the etiology of altered Ca metabolism in essential hypertension, we studied parameters, i.e., maximal initial reaction velocity (Vmax) and Michaelis constant (Km), of Ca activation kinetics of Ca2(+)-ATPase in membrane fractions (isolated by a sucrose gradient) from platelets of blacks and whites, 27 of whom were essential hypertensives, 17 of whom were normotensives with a family history of essential hypertension, and 10 of whom were normotensives without a family history of the disease. The Vmax of hypertensives was significantly lower than in normotensives without a family history of essential hypertension (hypertensives, 14.99 +/- 1.71 nmol Pi.mg protein-1.min-1; normotensives, positive family history, 22.67 +/- 3.17 nmol Pi.mg protein-1.min-1; normotensives, negative family history, 27.54 +/- 4.37 nmol Pi.mg protein-1.min-1; overall, P = 0.0078). The Km was lower in both hypertensives and normotensives with a positive family history of essential hypertension as compared with normotensives with a negative family history of the disease (hypertensives, 1.70 +/- 0.23 microM; normotensives, positive family history, 1.38 +/- 0.2 microM; normotensives, negative family history, 2.79 +/- 0.58 microM; overall, P = 0.0251). Furthermore, the Km in whites was inversely related to plasma renin activity (r = 0.50; P less than 0.005). We propose that a lower Vmax for Ca2(+)-ATPase may play a role in the higher level of free Ca in platelets of essential hypertensives and that a higher affinity of the enzyme to Ca may reflect a process compensating for the lower Vmax. We also suggest that a higher Km for Ca2(+)-ATPase in juxtaglomerular cells of whites would result in blunting the release of renin.

Distributed-activation kinetics of

1992 ◽  
Vol 23 (11) ◽  
pp. 2987-2998 ◽  
Author(s):  
Minfa Lin ◽  
Gregory B. Olson ◽  
Morris Cohen
Keyword(s):  
Activation Kinetics ◽  
Kinetics Of

scholarly journals Basolateral Na(+)-H+ antiporter. Mechanisms of electroneutral and conductive ion transport.

1994 ◽  
Vol 103 (5) ◽  
pp. 895-916 ◽  
Author(s):  
M A Post ◽  
D C Dawson
Keyword(s):  
Cation Exchange ◽  
Current Flow ◽  
Relative Proportion ◽  
Extracellular Fluid ◽  
Proton Gradient ◽  
Na Transport ◽  
Activation Kinetics ◽  
High Affinity Site ◽  
Kinetics Of ◽  
Proton Currents

The basolateral Na-H antiporter of the turtle colon exhibits both conductive and electroneutral Na+ transport (Post and Dawson. 1992. American Journal of Physiology. 262:C1089-C1094). To explore the mechanism of antiporter-mediated current flow, we compared the conditions necessary to evoke conduction and exchange, and determined the kinetics of activation for both processes. Outward (cell to extracellular fluid) but not inward (extracellular fluid to cell) Na+ or Li+ gradients promoted antiporter-mediated Na+ or Li+ currents, whereas an outwardly directed proton gradient drove inward Na+ or Li+ currents. Proton gradient-driven, "counterflow" current is strong evidence for an exchange stoichiometry of > 1 Na+ or Li+ per proton. Consistent with this notion, outward Na+ and Li+ currents generated by outward Na+ or Li+ gradients displayed sigmoidal activation kinetics. Antiporter-mediated proton currents were never observed, suggesting that only a single proton was transported per turnover of the antiporter. In contrast to Na+ conduction, Na+ exchange was driven by either outwardly or inwardly directed Na+, Li+, or H+ gradients, and the activation of Na+/Na+ exchange was consistent with Michaelis-Menten kinetics (K1/2 = 5 mM). Raising the extracellular fluid Na+ or Li+ concentration, but not extracellular fluid proton concentration, inhibited antiporter-mediated conduction and activated Na+ exchange. These results are consistent with a model for the Na-H antiporter in which the binding of Na+ or Li+ to a high-affinity site gives rise to one-for-one cation exchange, but the binding of Na+ or Li+ ions to other, lower-affinity sites can give rise to a nonunity, cation exchange stoichiometry and, hence, the net translocation of charge. The relative proportion of conductive and nonconductive events is determined by the magnitude and orientation of the substrate gradient and by the serosal concentration of Na+ or Li+.

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