Cooperativity state transitions

Raimondi M, Cooper DL (1999) Ab Initio Modern Valence Bond Theory. 203 105-120 Rao CNR, Seikh MM, Narayana C (2004) Spin-State Transition in LaCoOj and Related Materials. 234 1-21... 

In the same line, [Fe(qsal)2][Ni(dmit)2].2CH3CN has also been proven to show a cooperative spin transition based on n-n interactions between ligands [105]. Moreover, this compound is also one of the rare Fenl complex to exhibit the light-induced excited spin state trapping (LIESST) effect. 

Figure 13.1 Microcalorimetry scans displaying Tm values for interleukin-1 receptor (IL-1R type I). The inlay displays the unfolding of IL-1R (I) showing the ACp measured as the baseline difference between the native (N) and denatured (D) states for two independent scans. Thermal unfolding of IL-1R (I) is composed of three cooperative unfolding transitions, labeled 1, 2, and 3.

Haley MM, Pak JJ, Brand SC (1999) Top Curr Chem 201 81 HOger S (1999) J Polym Sci A Polym Chem 37 2685 Bunz UHF, Rubin Y, Tobe Y (1999) Chem Soc Rev 28 107 Faust R (1998) Angew Chem Int Ed 37 2825 Moore JS (1997) Acc Chem Res 30 402 Zhao D, Moore JS (2003) Chem Commun 807 Nelson JC,Saven JG,Moore JS,Wolynes PG (1997) Science 277 1793 Shetty AS, Zhang J, Moore JS (1996) J Am Chem Soc 118 1019 Prince RB,Saven JG,Wolynes PG,Moore JS (1999) J Am Chem Soc 121 3114 Hill DJ, Moore JS (2002) Proc Natl Acad Sci USA 99 5053 Cantor CR, Schimmel PR (1980) Biophysical chemistry. Freeman, San Francisco Prince RB (2000) Phenylene ethynylene foldamers cooperative conformational transition, twist sense bias, molecular recognition properties, and solid-state organization. PhD thesis. University of Illinois at Urbana-Champaign... 

The cw-l,2-bis(diphenylphosphino)ethene complexes [Fe(Ph2PCH=CHPPh2)2X2], X = C1 or Br, undergo pressure-induced spin-state transitions at about 8kbar for the chloro complex, about 60 kbar for the bromo complex. The difference is ascribed to the difference in ligand field strengths and lattice cooperativity. ... 

NMR evidence 115 demonstrated that a designed 20-residue peptide (betanova) adopts a three-stranded (3-sheet in water CD was also measured but the spectrum was not shown. The CD at 217 nm is negative and was used to monitor the thermal unfolding of the peptide. CD and fluorescence indicate a cooperative thermal transition. These CD and fluorescence data can be interpreted as evidence for a two-state cooperative thermal transition. However, a... 

There is some evidence that the strength of intermolecular forces determines the degree of cooperativity and the rate of spin state interconversion in the lattice (154,155). This is a reasonable hypothesis, for it assumes a continuum of behavior, from very weak interactions, which reflect intramolecular properties, to strong intermolecular forces, which cause cooperative phase transitions and abrupt spin state changes. Neutral complexes with a molecular lattice and little or no hydrogen bonding between the molecules, such as some iron(III)... 

Both the denaturation process in proteins and the melting transition (also referred to as the helix-to-coil transition) in nucleic acids have been modeled as a two-state transition, often referred to as the all-or-none or cooperative model. That is, the protein exists either in a completely folded or completely unfolded state, and the nucleic acid exists either as a fully ordered duplex or a fully dissociated monoplex. In both systems, the conformational flexibility, particularly in the high-temperature form, is great, so that numerous microstates associated with different conformers of the biopolymer are expected. However, the distinctions between the microstates are ignored and only the macrostates described earlier are considered. For small globular proteins and for some nucleic acid dissociation processes,11 the equilibrium between the two states can be represented as... 

The SC state transition can be characterized as a non-adiabatic sudden increase of the cooperative kinetic effect at lattice energy stabilization (NASICKELES). It is exactly participation of the nuclear kinetic energy... 

Hen egg-white lysozyme, lyophilized from aqueous solutions of different pH from pH 2.5 to 10.0 and then dissolved in water and in anhydrous glycerol, exhibits a cooperative conformational transition in both solvents occurring between 10 and 100°C (Burova, 2000). The thermal transition in glycerol is reversible and equilibrium follows the classical two-state mechanism. The transition enthalpies AHm in glycerol are substantially lower than in water, while transition temperatures Tm are similar to values in water, but follow similar pH dependences. The transition heat capacity increment ACp in glycerol does not depend on the pH and is 1.25 0.31 kj (mol K) 1 compared to 6.72 0.23 kj (mol K)-1 in water. Thermodynamic analysis of the calorimetric data reveals that the stability of the folded conformation of lysozyme in glycerol is similar to that in water at 20-80°C but exceeds it at lower and higher temperatures. 

Fig. 2. Temperature dependence of (a) the lattice constants of a La7/8Sri/8Mn03 single crystal (figure taken from Ref. [10]), (b) the resistivity, and (c) the low-field magnetic moment. The cooperative JT transition at Tjt = 269 K results in a doubling of the resistivity and a sharp drop of the magnetic moment (see inset in (c)). Below the temperature TCo = 147 K the crystal goes into a charge-ordered state and the CJT effect vanishes.

The theoretical treatment of a solid-state transition involving covalent (localized) vs. conduction (delocalized) electronic transformation was first enunciated by Mott [44], By considering the Pauli Exclusion Principle and the electron-electron interaction during the transformation, it was shown that such transition will be critically dependent upon the inter-atomic distances. The number of electrons already existing in the conduction state will in turn influence the critical inter-atomic distances and the transition therefore, it is necessarily a cooperative phenomenon. Later, in a theoretical treatment of the same subject, but based on a different context, Goodenough [45] has shown that the transition is likely to be second-order if the number of electrons per like atom is non-integral. Further, a crystallographic distortion is a prominent manifestation of such a transition. 

Veprintsev, D.B., Permyakov, S.E., Permyakov, E.A., Rogov, V.V., Cawthern, K.M., and Berliner, L.J. 1997. Cooperative thermal transitions of bovine and human apo-alpha-lactalbumins Evidence for a new intermediate state. FEBS Lett 412(3) 625—628. 

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