Denaturation, kinetics

Another research group has previously conducted tests on the denaturation kinetics and has reported the data below. 

The whey proteins, which represent about 20% of the proteins of bovine milk, are typical globular proteins with high levels of secondary and tertiary structures, and are, therefore, susceptible to denaturation by various agents, including heat. The denaturation kinetics of whey proteins, as measured by loss of solubility in saturated NaCl at pH 4.6, are summarized in Figure... 

Hinrichs, J. and Rademacher, B. 2004. High pressure thermal denaturation kinetics of whey proteins. J. Dairy Res. 71(4) 480-488. 

SPR detection of hybridization and denaturation kinetics for tethered ssDNA thiol on gold was achieved by monitoring the gain or loss of DNA at the interface in the presence of an applied electrostatic field. Redox reactions were avoided and the current measured was limited to the capacitive, non-faradaic charging current, at selected potentials applied to the gold electrode interface, as described by Georgiadis and co-workers [47], The specific DNA thiol monolayer films were robust and could be reused. 

S. Yoshioka, Y. Aso, K. Izutsu, and S. Kojima, Is stability prediction possible for protein drugs Denaturation kinetics of 3-galactosidase in solution, Pharm. Res. 11, 1721-1725(1994). 

Barclay C, Moore D, Lander S et al. (1990) Heat denaturation kinetics of lignin peroxidases from Phanarochaete chrysosporium. Enzyme Microb Technol 12 778-782... 

Another research group previously conducted tests on protein denaturation kinetics and reported the data below. Determine if the data are consistent with the principles of the kinetics of cell death phenomena. Estimate the first-order rate constant for cell death at the conditions employed in the sterilization reactor. Will the proposed process meet the standards for protein degradation ... 

The denaturation kinetics of proteins during convective drying can generally be expressed by the first-order reaction kinetics model (Equation 49.5) (Skelte and Anthony, 1996 Oldfield et al., 1998 Haque et al., 2013b) ... 

An application of Equations 49.5 and 49.6 to predict denaturation kinetics of major whey protein constituents such as... 

Haque, M.A. Putranto, A. Aldred, R Chen, J. Adhikari, B. Drying and denaturation kinetics of whey protein isolate (WPI) during convective air drying process. Drying Technology, 2013b, 31,1532-1544. 

The major problem for topologically closed DNA at high temperature is degradation. This phenomenon can be followed by spectrophotometry, as illustrated in Fig. 1. When plasmid DNA is incubated at extreme temperatures (here, 107°), one observes a time-dependent increase in optical density at 257 nm that corresponds to the denaturation of the molecule. The denaturation kinetics reflect the introduction of nicks in the DNA backbone. Indeed, as soon as the topological constraints are relieved in one molecule by cleavage of one strand, this molecule is denatured at the temperature of the experiment, which is well above the of nicked DNA. The rate of denaturation is thus proportional to the number of intact molecules remaining at any time in the solution. It is, therefore, very important to limit the rate of DNA cleavage as much as possible, both in vivo for hyperthermophiles... 

Teichroeb, J. H. Forrest, J. A. Jones, L. W. Size-dependent denaturing kinetics of bovine serum albumin adsorbed onto gold nanospheres. Eur. Phys. J. Part E. Soft Matter, 2008, 26(4), 411 15. 

When a protein is adsorbed to a hydrophobic surface, denaturation is often not an instantaneous phenomenon. Thus, the extent of unfolding will increase with increasing time of adsorption. Both Karger and Hearn et al. [40] have monitored this residency effect on reversed-phase and hydrophobic interaction columns using a combination of techniques including derivative spectroscopy. The Hearn group also studied denaturation kinetics in size exclusion chromatography in the presence of the powerful denaturant urea. 

Since the reversibility of relatively few denaturation reactions has been demonstrated, it is not surprising that most denaturation studies have been concerned with the kinetics of denaturation. The most commonly used techniques are optical rotatory and precipitation methods. An example of the pH dependence of the rate of a denaturation reaction over a wide range of temperature and pH is shown in Fig. 59. The purpose of the final section of this chapter is to show how side-chain hydrogen bonding can lead to such pH-dependent denaturation kinetics (Laskowski and Scheraga, 1961). 

Fig. 2 shows Log (dN/dt) Q vs Log N(0) at T = 54°C, where N(0) is the initial concentration of met-hemoglobin and (dN/dt) Q is the initial slope of the denaturation kinetics. Fig. 2 clearly shows that the reaction is first order with respect to protein concentration and thus that the denaturation process can be considered, in our concentration range, as a unimolecolar reaction. This is true both in H O and DoOj within the entire range of temperatures examined (52-63°C). 

Fig. 2 - Initial slope of the denaturation kinetics in normal water...

Fig. 3 - Denaturation kinetics of met-hemoglobin. Met-hemoglobin concentration 3xl0 M (tetramer) O.IM phosphate buffer...

Fig. 3 shows denaturation kinetics of met-hemoglobin at T=60°C in normal water and in solutions containing various proportions of D2O in H2O. Actual values are shown in Table I. Deuterium oxide stabilizes the native conformation of met-hemoglobin this effect increases progressively by increasing the amount of D2O in the solution moreover it does not depend upon the time of incubation of the sample, fpr incubation times greater than - 4 hrs. 

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