Proteins in electric fields and pressure fields: basic aspects

Köhler, M.; Friedrich, J.; Fidy, Judit

doi:10.1016/s0167-4838(98)00098-3

Cited by 66 publications

(74 citation statements)

References 80 publications

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“…2b), which yield exactly the same results for both situations, namely 6.5 nm/GPa. Notice that at moderate pressure levels, the pressure shift of the fluorescence emission is supposed to be proportional to the solvent shift (31). This implies that, after denaturation, there is no significant influence of the protein on the chromophore.…”

Section: [1]mentioning

confidence: 98%

Temperature and pressure dependence of protein stability: The engineered fluorescein-binding lipocalin FluA shows an elliptic phase diagram

Wiedersich

Köhler

Skerra

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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We have measured the equilibrium constant for the denaturation transition of the engineered fluorescein-binding lipocalin FluA as a function of pressure and temperature, taking advantage of the fact that the ligand's fluorescence is almost fully quenched when complexed with the folded protein, but reversibly reappears on denaturation. From the equilibrium constant as a function of pressure and temperature all of the involved thermodynamic parameters of protein folding, in particular the changes in entropy and volume, compressibility, thermal expansion, and specific heat, were deduced in a global fitting procedure. Assuming that these parameters are independent of temperature and pressure, we can demonstrate from the ratio of ⌬␤, ⌬␣ 2 , ⌬Cp that the phase diagram of protein folding assumes an elliptic shape. Furthermore, we can show that the thermodynamic condition for such an elliptic phase diagram is related to the degree of correlation between the fluctuations of the changes in volume and enthalpy at the phase boundary. For the protein investigated this correlation is low, as generally expected for highly degenerate systems. Our study suggests that the elliptic phase diagram is a consequence of the inherent conformational disorder of proteins and that it may be viewed as the thermodynamic manifestation of the high degeneracy of conformational energies that is characteristic for this class of macromolecules.anticalin ͉ denaturation ͉ engineering ͉ folding ͉ thermodynamics

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Section: [1]mentioning

confidence: 98%

Temperature and pressure dependence of protein stability: The engineered fluorescein-binding lipocalin FluA shows an elliptic phase diagram

Wiedersich

Köhler

Skerra

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…The electric field, F, affecting the electronic state of P is considered as a linear combination of the three vector components of the applied electric field (F a ), the pocket field due to the presence of apoproteins (F p ), and the electrostatic field induced by the presence of carotenoid (F c ) [48] (1)…”

Section: Theoretical Model To Analyze the Stark Spectramentioning

confidence: 99%

“…Although the idea to describe the electrostatic field as a summation of the applied and pocket fields has already been suggested [48], the F c term has been introduced additionally in order to clarify the effect of the presence of carotenoid.…”

Section: Theoretical Model To Analyze the Stark Spectramentioning

confidence: 99%

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Structures and functions of carotenoids bound to reaction centers from purple photosynthetic bacteria

Hashimoto

Fujii

Yanagi

et al. 2006

Pure and Applied Chemistry

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The photoprotective function of 15,15'-cis-carotenoids bound to the photosynthetic reaction centers (RCs) of purple bacteria has been studied using carotenoids reconstituted into carotenoidless RCs from Rhodobacter sphaeroides strain R26.1. The triplet-energy level of the carotenoid has been proposed to affect the quenching of the triplet state of special-pair bacteriochlorophyll (P). This was investigated using microsecond flash photolysis to detect the carotenoid triplets as a function of the number of conjugated double bonds, n. The carotenoid triplet signals were extracted by using singular-value decomposition (SVD) of the huge matrices data, and were confirmed for those having n = 8 to 11. This interpretation assumes that the reconstituted carotenoids occupy the same binding site in the RC. We have been able to confirm this assumption using X-ray crystallography to determine the structures of carotenoidless, wild-type carotenoid-containing, and 3,4-dihydro-spheroidene-reconstituted RCs. The X-ray study also emphasized the importance of the methoxy group of the carotenoids for binding to the RCs. Electroabsorption (Stark) spectroscopy was used to investigate the effect of the carotenoid on the electrostatic field around P. This electrostatic field changed by 10 % in the presence of the carotenoid.

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“…(ii) The dispersive (nonsingle exponential) hole-growth kinetics (HGK) that reflect structural heterogeneity (10). (iii) The permanent dipole moment change (⌬ ) of the S 0 3 S 1 transition that is obtained by measuring the response of the ZPH (broadening and͞or splitting) to an external electric (Stark) field (26). Here it is the matrix-induced contribution to ⌬ that is of interest.…”

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confidence: 99%

Single-cell nonphotochemical hole burning of ovarian surface epithelial carcinoma and normal cells

Walsh

Matsuzaki

Reinot

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Persistent spectral nonphotochemical hole-burning (NPHB) spectroscopy has recently been applied to dye molecules in cells. The sensitivity of NPHB to the nanoenvironment of the probe is well established. It has been shown that NPHB applied to bulk suspensions of cultured human cells can distinguish between normal and cancer cells. Thus, NPHB has potential as a diagnostic cancer tool. For this reason, the methodology is referred to as hole-burning imaging, by analogy with MRI. The optical dephasing time (T 2) of the dye in hole-burning image replaces the proton T1 relaxation time in MRI. In addition to the T 2 mode of operation, there are four other modes including measurement of the spectral hole growth kinetics (HGK). Reported here is that the selectivity and sensitivity of NPHB operating in the HGK mode allow for distinction between normal and carcinoma cells at the single-cell level. The ovarian cell lines are ovarian surface epithelial cells with temperature-sensitive large T antigens (analogously normal) and ovarian surface epithelial carcinoma (OV167) cells. The mitochondrial specific dye used was rhodamine 800 (Molecular Probes). This carbocationic dye is highly specific for the outer and inner membranes of mitochondria. In line with the results for bulk suspensions of the two cell lines, the hole-burning efficiency for OV167 cells was found to be significantly higher than that for normal cells. Theoretical analysis of the HGK data leads to the conclusion that the degree of structural heterogeneity for the probe-host configurations in OV167 cells is lower than in the normal cells. Possible reasons for this are given.

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Proteins in electric fields and pressure fields: basic aspects

Cited by 66 publications

References 80 publications

Temperature and pressure dependence of protein stability: The engineered fluorescein-binding lipocalin FluA shows an elliptic phase diagram

Temperature and pressure dependence of protein stability: The engineered fluorescein-binding lipocalin FluA shows an elliptic phase diagram

Structures and functions of carotenoids bound to reaction centers from purple photosynthetic bacteria

Single-cell nonphotochemical hole burning of ovarian surface epithelial carcinoma and normal cells

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