Role of metals in enzymatic reactions. Part 3.—Kinetics of complex formation in model systems involving zinc and pyridine-2-azo-p-dimethylaniline

1971 ◽  
Vol 67 (0) ◽  
pp. 786-793 ◽  
Author(s):  
G. R. Cayley ◽  
D. N. Hague
Keyword(s):  
Complex Formation ◽  
Model Systems ◽  
Enzymatic Reactions ◽  
Kinetics Of

Modelling of DNA Complexes with Distamycin Analogues Using an ab initio Continuum Solvent Model

2000 ◽  
Vol 65 (5) ◽  
pp. 631-643 ◽  
Author(s):  
Petr Bouř ◽  
Vladimír Král
Keyword(s):  
Complex Formation ◽  
Ab Initio ◽  
Polar Solvent ◽  
Molecular Shape ◽  
Conformational Flexibility ◽  
Model Systems ◽  
Dna Complexes ◽  
Solvent Model ◽  
Dna Complex

Model systems related to non-covalent minor groove DNA complexes with distamycin analogues were investigated using the Turbomole and Gaussian quantum chemical packages. The role of molecular shape, electrostatic field and conformer energies in the complex formation was discussed. The ab initio calculations included the COSMO solvent model. If compared to vacuum computations, polar solvent significantly destabilizes such complexes and increases conformational flexibility of distamycin. The DNA complex formation appears to be driven mainly by entropy lowering and complementarity of molecular shapes. The NH moiety of the amide group preferably points to the base pair according to the computations, in agreement with experimental data.

Role of Complex Formation in the Polymerization Kinetics of Modified Epoxy−Amine Systems

2005 ◽  
Vol 38 (6) ◽  
pp. 2281-2288 ◽  
Author(s):  
Steven Swier ◽  
Guy Van Assche ◽  
Wendy Vuchelen ◽  
Bruno Van Mele
Keyword(s):  
Complex Formation ◽  
Polymerization Kinetics ◽  
Epoxy Amine ◽  
Modified Epoxy ◽  
Kinetics Of

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

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