Diffusion coefficients of anticancer drugs and compounds having a similar structure at 30 �C

Nishida, K.; Ando, Yutaka; Kawamura, Hideo

doi:10.1007/bf01411520

Cited by 14 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For adenosyl radical in solution the radius r can be estimated as 4.1 Å (based on measurements of the molar volume of adenosine). , The radius used for adenosyl is slightly larger than the 3.8 Å radius estimated from the calculated van der Waals volume, which may be important when we consider the other alkyl radicals below. The estimate for adenosyl is slightly smaller than the 4.42 Å radius obtained in the diffusion measurements of adenosine . The radius of the cobalamin radical is estimated at 7.1 Å based on measurements of the partial molar volume of simple cobalamins .…”

Section: Discussionsupporting

confidence: 77%

Solvent-Dependent Cage Dynamics of Small Nonpolar Radicals: Lessons from the Photodissociation and Geminate Recombination of Alkylcobalamins

et al. 2009

View full text Add to dashboard Cite

Time-resolved transient absorption spectroscopy was used to investigate the primary geminate recombination and cage escape of alkyl radicals in solution over a temperature range from 0 to 80 degrees C. Radical pairs were produced by photoexcitation of methyl, ethyl, propyl, hexylnitrile, and adenosylcobalamin in water, ethylene glycol, mixtures of water and ethylene glycol, and sucrose solutions. In contrast to previous studies of cage escape and geminate recombination, these experiments demonstrate that cage escape for these radical pairs occurs on time scales ranging from a hundred picoseconds to over a nanosecond as a function of solvent fluidity and radical size. Ultrafast cage escape (<100 ps) is only observed for the methyl radical where the radical pair is produced through excitation to a directly dissociative electronic state. The data are interpreted using a unimolecular model with competition between geminate recombination and cage escape. The escape rate constant, k(e), is not a simple function of the solvent fluidity (T/eta) but depends on the nature of the solvent as well. The slope of k(e) as a function of T/eta for the adenosyl radical in water is in near quantitative agreement with the slope calculated using a hydrodynamic model and the Stokes-Einstein equation for the diffusion coefficients. The solvent dependence is reproduced when diffusion constants are calculated taking into account the relative volume and mass of both solvent and solute using the expression proposed by Akgerman (Akgerman, A.; Gainer, J. L. Ind. Eng. Chem. Fundam. 1972, 11, 373-379). Rate constants for cage escape of the other radicals investigated are consistently smaller than the calculated values suggesting a systematic correction for radical size or coupled radical pair motion.

show abstract

Section: Discussionsupporting

confidence: 77%

Solvent-Dependent Cage Dynamics of Small Nonpolar Radicals: Lessons from the Photodissociation and Geminate Recombination of Alkylcobalamins

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Such analysis is consistent with a diffusion coefficient of (1.25 ( 0.2) × 10 5 cm s -1 ; this value is comparable to that found within the literature from independent measurements, leading to the confirmation that the analysis is of the correct form. 32,33 The error associated with the diffusion coefficient is a result of the experimental variation in the measured peak height; this variation was greater at higher concentrations and is likely a result of the potential dependence of the surface structure. 15 Figure 7 shows the average result for all three concentrations plotted as peak current against the square root of the scan rate.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Oxidation of Adenine: A Mixed Adsorption and Diffusion Response on an Edge-Plane Pyrolytic Graphite Electrode

et al. 2010

View full text Add to dashboard Cite

Understanding the oxidation of the purines adenine and guanine is primary to improving electrochemical methods of DNA detection and analysis. Adenine in the solution phase is reported to undergo a complex electrochemical oxidation mechanism that is overall a -6H + , -6eprocess, involving irreversible chemical steps. The observed voltammetry associated with the oxidation of adenine is strongly dependent upon the electrode used; this is a reflection of both the kinetics of oxidation and strength of bonding to the electrode surface, both of which are surface specific. Two main cases are presented within the article, one in which the adsorption of adenine to the electrode surface is strong, as is the case with gold and one in which the bonding is weaker, as found with graphitic surfaces. In the case of gold, adsorption is strong enough to prevent the adenine oxidation to be observed within the electrochemical window and further to this the formed monolayer prevents oxidation of the gold surface. With graphitic surfaces adsorption is weaker and as such oxidation of adenine is observed, this oxidative signal is demonstrated to be due to the oxidation of both surface bound and solution phase species. A generic method for analyzing the peak currents for reversible electron transfers coupled with an irreversible chemical process is presented. The analysis is dependent upon knowledge of the number of electrons transferred prior to the first chemically irreversible process and the total number of electrons transferred during the redox process. In addition to this, the analysis provides a description for the peak height of voltammetric waves that have contributions from both adsorbed and solution phase species, with these two processes being resolved through their differing dependencies with scan rate. The methodology is then used for the analysis of the oxidation of adenine on an edge-plane pyrolytic graphite electrode, where the influences on peak current from adsorption and diffusion are demonstrated. The diffusion coefficient for adenine is found to be (1.25 ( 0.2) × 10 5 cm s -1 , which is in close agreement to that found by independent measurements reported in the literature. The adsorption of adenine at low concentrations to the electrode surface, is shown to exhibit a linear dependence of coverage with the solution phase concentration, where the surface coverage is given by Γ ) KC* with a measured K value of (1.7 ( 0.1) × 10 -3 cm and C* is the solution phase concentration.

show abstract

“…1 ). The value τ trap, 0.5 = 60 ns may be directly calculated from the Smoluchowski diffusion equation ( Supplementary equation S3 ), using the measured diffusion constant of uracil 41 . Given that τ trap, 0.5 =τ hop under the condition where 50% of the hopping events are trapped, the Einstein equation may then be used to calculate the distance (< r hop > = 7 nm) traveled by hUNG in a hopping event of duration τ hop using a calculated D 3 = 1.4 × 10 8 nm 2 /s ( Supplementary Methods ) for hUNG ( eq 5 ).…”

Section: Discussionmentioning

confidence: 99%

Timing facilitated site transfer of an enzyme on DNA

2012

View full text Add to dashboard Cite

Many enzymes that react with specific sites in DNA exhibit the property of facilitated diffusion, where the DNA chain is used as a conduit to accelerate site location. Despite the importance of such mechanisms in gene regulation and DNA repair, there have been few viable approaches to elucidate the microscopic process of facilitated diffusion. Here we describe a new method where a small molecule trap (uracil) is used to clock a DNA repair enzyme as it hops and slides between damaged sites in DNA. The “molecular clock” provides unprecedented information: the mean length for DNA sliding, the 1D sliding constant, the maximum hopping radius and time frame for DNA hopping events. In addition, the data establish that the DNA phosphate backbone is a sufficient requirement for DNA sliding.

show abstract

Diffusion coefficients of anticancer drugs and compounds having a similar structure at 30 �C

Cited by 14 publications

References 4 publications

Solvent-Dependent Cage Dynamics of Small Nonpolar Radicals: Lessons from the Photodissociation and Geminate Recombination of Alkylcobalamins

Solvent-Dependent Cage Dynamics of Small Nonpolar Radicals: Lessons from the Photodissociation and Geminate Recombination of Alkylcobalamins

Electrochemical Oxidation of Adenine: A Mixed Adsorption and Diffusion Response on an Edge-Plane Pyrolytic Graphite Electrode

Timing facilitated site transfer of an enzyme on DNA

Contact Info

Product

Resources

About