Titration isothermal

Alternative variations of the isothermal titration technique utilize CO adsorption followed by reaction with gaseous 02. Experiment has shown that similar Nc values are obtained.1,19... 

As already noted the strength of chemisorptive bonds can be varied in situ via electrochemical promotion. This is the essence of the NEMCA effect. Following initial studies of oxygen chemisorption on Ag at atmospheric pressure, using isothermal titration, which showed that negative potentials causes up to a six-fold decrease in the rate of 02 desorption,11 temperature programmed desorption (TPD) was first used to investigate NEMCA.29... 

Table 5 Binding of palmatine to homo and hetero polymer of AT as revealed from isothermal titration calorimetry [176]...

Fig. 14 Isothermal titration calorimetry for the binding of berberine (a and d) and pal-matine (b and e) to tRNA. Reprinted from [214] with permission from Elsevier...

Table 8 Binding parameters of t-RNA complexation with berberine and palmatine obtained from spectrophotometric, spectrofluorimetric and isothermal titration calorimetric study [214]... 

Alkaloids Spectrophotometry Spectrofluorimetry Isothermal titration calorimetry ... 

Ion transfer, 14 (1977) 1 Irinotecan, anticancer agent, 34 (1997) 68 Isothermal titration calorimetry, in drug design, 38 (2001) 309... 

Instrumentation. H and NMR spectra were recorded on a Bruker AV 400 spectrometer (400.2 MHz for proton and 100.6 MHz for carbon) at 310 K. Chemical shifts (< are expressed in ppm coupling constants (J) in Hz. Deuterated DMSO and/or water were used as solvent chemical shift values are reported relative to residual signals (DMSO 5 = 2.50 for H and 5 = 39.5 for C). ESl-MS data were obtained on a VG Trio-2000 Fisons Instruments Mass Spectrometer with VG MassLynx software. Vers. 2.00 in CH3CN/H2O at 60°C. Isothermal titration calorimetry (ITC) experiments were conducted on a VP isothermal titration calorimeter from Microcal at 30°C. 

T. K. Dam and C. F. Brewer, Multivalent protein-carbohydrate interactions Isothermal titration microcalorimetry studies, Methods Enzymol., 379 (2004) 107-128. 

Further experiments focused therefore on [RuCl(en)(r 6-tha)]+ (12) and [RuCl(rj6-p-cym)(en)]+ (22), which represent the two different classes, and their conformational distortion of short oligonucleotide duplexes. Chemical probes demonstrated that the induced distortion extended over at least seven base pairs for [RuCl(rj6-p-cym)(en)]+ (22), whereas the distortion was less extensive for [RuCl(en)(rj6-tha)]+ (12). Isothermal titration calorimetry also showed that the thermodynamic destabilization of the duplex was more pronounced for [RuCl(r 6-p-cym)(en)]+ (22) (89). DNA polymerization was markedly more strongly inhibited by the monofunctional Ru(II) adducts than by monofunctional Pt(II) compounds. The lack of recognition of the DNA monofunctional adducts by HMGB1, an interaction that shields cisplatin-DNA adducts from repair, points to a different mechanism of antitumor activity for the ruthenium-arenes. DNA repair activity by a repair-proficient HeLa cell-free extract (CFE) showed a considerably lower level of damage-induced DNA repair synthesis (about six times) for [RuCl(en)(rj6-tha)] + compared to cisplatin. This enhanced persistence of the adduct is consistent with the higher cytotoxicity of this compound (89). 

The principles of titration calorimetry will now be introduced using isoperibol continuous titration calorimetry as an example. These principles, with slight modifications, can be adapted to the incremental method and to techniques based on other types of calorimeters, such as heat flow isothermal titration calorimetry. This method, which has gained increasing importance, is covered in section 11.2. 

Another area where titration calorimetry has found intensive application, and where the importance of heat flow versus isoperibol calorimetry has been growing, is the energetics of metal-ligand complexation. Morss, Nash, and Ensor [225], for example, used potenciometric titrations and heat flow isothermal titration calorimetry to study the complexation of UO "1" and trivalent lanthanide cations by tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA), in aqueous solution. Their general goal was to investigate the potential application of THFTCA for actinide and lanthanide separation, and nuclear fuels processing. The obtained results (table 11.1) indicated that the 1 1 complexes formed in the reaction (M = La, Nd, Eu, Dy, andTm)... 

E. Freire, O. L. Mayorga, M. Straume. Isothermal Titration Calorimetry. Anal. 

Christensen, T., B. Svensson, and B.W. Sigurskjold. 1999. Thermodynamics of reversible and irreversible unfolding and domain interactions of glucoamylase from Aspergillus niger studied by differential scanning and isothermal titration calorimetry. Biochemistry 38 6300-6310. 

Jelesarov, I. and H.R. Bosshard. 1999. Isothermal titration calorimetry and differential scanning calorimetry as complementary tools to investigate the energetics of biomolecular recognition. J Mol Recognit 12 3-18. 

Livingstone, J.R. 1996. Antibody characterization by isothermal titration calorimetry. Nature 384 491 192. 

Baker, B.M. and K.P. Murphy. 1996. Evaluation of linked protonation effects in protein binding reactions using isothermal titration calorimetry. Biophys J 71 2049-2055. 

Srivastava, D.K., S. Wang, and K.L. Peterson. 1997. Isothermal titration microcal-orimetric studies for the binding of octenoyl-CoA to medium chain acyl-CoA dehydrogenase. Biochemistry 36 6359-6366. 

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