Temperature-jump studies

Temperature jump studies were performed in combination with stopped-flow experiments94 in response to criticism as to the reliability of temperature jump experiments26,142 and divergent interpretation of the kinetics. In particular, the suggestion from pressure jump experiments that the association step is diffusive in nature... 

Finally, no dependence on the temperature, DNA concentration and salt concentration was observed for a temperature jump study using ct-DNA that was not sonicated.27 Based on these results the authors concluded that only large-scale dynamics of the DNA were responsible for the binding kinetics of 1 to DNA, and they suggested that studies with short length DNA may not be relevant for in vivo situations. 

Temperature jump studies on the binding dynamics of 5 with ct-DNA and T2 Bacteriophage DNA showed two lifetimes in the relaxation kinetics.117 The observed... 

The non-linear dependence of the relaxation process on the DNA concentration was also observed in stopped-flow experiments and the same mechanism, i.e. fast pre-equilibrium followed by a slow intercalation step, was proposed." This latter study did not report values for the individual rate constants. The mechanism proposed in Scheme 4 was employed in subsequent studies despite the criticism on the accuracy for the data related to the fast kinetic component (see below). The original temperature jump study also showed that the relaxation kinetics depend on the structure of the DNA.117 The slower intercalation rate for 5 with T2 Bacteriophage DNA when compared to ct-DNA was ascribed to the glucosylation of the former DNA (Table 3). 

Table II summarizes a temperature jump study (14) of the reaction of hydroxide ion with various intramolecularly hydrogen bonded malonic acid monoanions and points up the fact that, as the steric hindrance increases, a considerable strengthening in the hydrogen bond occurs with a concomitant slowing down of the rate at which the reaction proceeds (generalization number 4). At the time the authors did not foresee that it would be possible to distinguish between whether the hydrogen bond was broken directly by the attacking base or whether, in fact, there first had to be a collapse of the hydrogen bond into an open form of the anion that would subsequently react with the base. Thus, they simply postulated the former mechanism (direct attack). ...

The His35, with coordinated His46 in close proximity, has frequently been suggested as a site for electron transfer reactivity of azurin. Two processes have been detected in a temperature-jump study on the equihbration of azurin with cytochrome C551, its physiological partner [57]. The fast process is assigned to electron transfer, and the slower process to a conversion between inactive and active forms of reduced azurin. It has been concluded that the active form is protonated. A second H-bonded form of His35 is believed to result from the protonation [2]. 

The relaxation approach has played an important role in our understanding of the mechanisms of complex formation in solution (Chap. 4) 39,i4o -pjjg qj computer programs has now eased the study of multiple equilibria. For example, four separate relaxation effects with t s ranging from 100 xs to 35 ms are observed in a temperature-jump study of the reactions of Ni with flavin adenine dinucleotide (fad) (Eqn. (8.121)). The complex relaxation... 

Brunori, M., Parr, S. R., Greenwood, C., and Wilson, M. T. (1975). A temperature-jump study of the reaction between azurin and cytochrome c oxidase from Pseudomonas aeruginosa. Biochem. J. 151, 185-188. 

Urbanke, C., and Wray, J. (2001). A fluorescence temperature-jump study of conformational transitions in myosin subfragment 1. Biochem.J. 358, 165—173. 

Dewey, T. G., and Turner, D. H. (1980). Laser temperature jump study of solvent effects on poly (adenylic acid) stacking. Biochemistry 19, 1681-1685. 

A temperature-jump study of the outer-sphere reduction of [RhCl6]2 (equation 288) showed that at 10aC the equilibrium constant is 9.08 (ji = 0.05 M) and the rate of both the forward and reverse reactions are approximately diffusion controlled (the lower limit of k[or is 2.5 x 109M I s-1).1240... 

Schilling, K. and Waldmann-Meyer, H., The interaction of bromophenol blue with serum albumin and gamma-globuhn in acid medium. Arch. Biochem. Biophys. 64, 291-301, 1956 Cohen, A.H., Temperature jump studies of the binding of bromophenol blue to beta-lactoglobulin in the vicinity of the N-R transition, J. Biol. Chem. 245,738-745,1970 Harruff, R.C. and Jenkins, W.T., The binding of bromophenol blue to aspartate aminotransferase. Arch. Biochem. Biophys. 

In a recent temperature-jump study [48] of the methanolysis of l,l-bis(p-dimethylaminophenyl)ethylene all rate coefficients shown in scheme (27) were measured and the mechanism was clearly identified. 

Various modes of data acquisition are available for selection to commensurate with experimental configurations. The raw data are further transferred to an off-line computer (IBM-XT) for post data treatments such as background correction, data smoothing, rescaling, etc. Generally, a set of sample hot stages is used for temperature jump studies one is controlled at an experimental temperature and the other is preheated below phase separation... 

In aqueous solutions of borate at low concentrations the main anionic species are B(0H)4 and B303(0H)4, with higher species likely to be present when the total borate concentration exceeds 0.2 M. With such solutions, temperature-jump studies" reveal the presence of two relaxation times longer than 10 sec (at pH 6 and 7.4). One of these is evident in the whole range pH 5-10 and is attributed to reaction (1), for which pK is 6.87,... 

In an early study the rates of reaction of fluorine oxide (F2O) with sodium hydroxide were investigated. Discussion of hydrolytic decomposition of the other halogens may conveniently begin with the temperature-jump study by Eigen and Kustin. This showed that the only significant steps for chlorine and bromine involve the intermediate X2OH , viz. 

Pasternack and co-workers have reported a series of detailed temperature-jump studies on mixed ligand complexes involved in the copper(ll) + bipyridine + glycine system [142], the copper(ll) + bipyridine + ethylene-diamine, of-alanine, and j3-alanine systems, and the cobalt(ll) + bipyridine + glycine system [143]. 

Interference from Ring-closure.—In 1966, Kustin, Pasternack, and Weinstock published a paper entitled Steric effects in fast metal complex substitution reactions , in which they reported a temperature-jump study involving the nickel(ii) and cobalt(ii) complexes with a- and jS-alanine. With a-alanine, the substitution at cobalt was significantly faster than at nickel, but with the jS-isomer, whereas the Ni + substitution rate was approximately the same as before, substitution at Co + was significantly slower. The rate constants shown in Table 4 were obtained for the 1 1... 

Smalley, I, L. Geng, A. Chen, S. Feldberg, N. Lewis, and G. Cali (2003). An indirect laser-induced temperature jump study of the influence of redox couple adsorption on heterogeneous electron transfer kinetics. Journal of Electroanalytical Chemistry 549, 13-24. 

Two studies have been made of the chromium(vi) oxidation of thiocyanate, - in which the reported dependence of the ligand concentration is substantially different. In keeping with the earlier observation that a complex between Cr and SCN is sufficiently stable with respect to redox at low [H+] to allow temperature-jump studies to be made (and hence to yield a value for the formation constant), Muirhead and Haight found an immediate increase in absorbance on mixing the reactants in the stopped-flow apparatus. The spectrum of the intermediate was derived using the continuous-flow method. Assuming the oxidation reaction to proceed via this complex, the rate law may be written in the form... 

In a temperature-jump study using a pulsed neodymium laser, Creutz and Sutin were able to study the interconversion between the low-spin planar CAig) and high-spin octahedral CA g) forms of the nickel(ii) complex of (17). The relaxation time was 0.30 ps at 23 °C and was, as expected, independent of the concentration of the complex. 

RAMAN LASER TEMPERATURE JUMP STUDY OF SOLVENT EFFECTS ON SIMPLE STACKING SYSTEMS... 

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