Retinol-binding protein is in the molten globule state at low pH

Bychkova, Valentina E.; Berni, Rodolfo; Rossi, Gian Luigi; Kutyshenko, V. P.; Ptitsyn, Oleg B.

doi:10.1021/bi00148a018

Cited by 141 publications

(93 citation statements)

References 38 publications

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“…, where θ obs (mdeg) is the experimental ellipticity, c (mol.dm ) is the protein concentration, l (cm) is the cell path length, and n is the number of residues in the protein [21].…”

Section: Methodsmentioning

confidence: 99%

Translational and Rotational Motions of Albumin Sensed by a Non-Covalent Associated Porphyrin Under Physiological and Acidic Conditions: A Fluorescence Correlation Spectroscopy and Time Resolved Anisotropy Study

Andrade¹,

Costa²,

Borst

et al. 2008

J Fluoresc

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The interaction between a free-base, anionic watersoluble porphyrin, TSPP, and the drug carrier protein, bovine serum albumin (BSA) has been studied by time-resolved fluorescence anisotropy (TRFA) and fluorescence correlation spectroscopy (FCS) at two different pH-values. Both rotational correlation times and translational diffusion times of the fluorescent species indicate that TSPP binding to albumin induces very little conformational changes in the protein under physiological conditions. By contrast, at low pH, a biexponential decay is obtained where a short rotational correlation time (7 int =1.2 ns) is obtained, which is likely associated to wobbling movement of the porphyrin in the protein binding site. These physical changes are corroborated by circular dichroism (CD) data which show a 37% loss in the protein helicity upon acidification of the medium. In the presence of excess porphyrin formation of porphyrin Jaggregates is induced, which can be detected by timeresolved fluorescence with short characteristic times. This is also reflected in FCS data by an increase in molecular brightness together with a decrease in the number of fluorescent molecules passing through the detection volume of the sample.

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“…, where θ obs (mdeg) is the experimental ellipticity, c (mol.dm ) is the protein concentration, l (cm) is the cell path length, and n is the number of residues in the protein [21].…”

Section: Methodsmentioning

confidence: 99%

Translational and Rotational Motions of Albumin Sensed by a Non-Covalent Associated Porphyrin Under Physiological and Acidic Conditions: A Fluorescence Correlation Spectroscopy and Time Resolved Anisotropy Study

Andrade¹,

Costa²,

Borst

et al. 2008

J Fluoresc

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“…The cooperative thermal transition at higher temperatures from the intermediate state of lysozyme in 25% HFA, indeed suggests a predominant role of inter-side-chain interactions in determining the stability of the partially folded state. The thermal denaturation of many molten globule states are known to be cooperative, e.g., apo-myoglobin, (Nishii et al, 1994), cytochrome c (Kuroda et al, 1992), and retinol binding protein (Bychkova et al, 1992), suggesting an ordered organization of the non-polar residues (Freire, 1995).…”

Section: Ans Bindingmentioning

confidence: 99%

Hexafluoroacetone hydrate as a structure modifier in proteins: Characterization of a molten globule state of hen egg‐white lysozyme

Bhattacharjya

Balaram

1997

Protein Science

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A molten globule-like state of hen egg-white lysozyme has been characterized in 25% aqueous hexafluoroacetone hydrate (HFA) by CD, fluorescence, NMR, and H/D exchange experiments. The far UV CD spectra of lysozyme in 25% HFA supports retention of native-like secondary structure while the loss of near UV CD bands are indicative of the overall collapse of the tertiary structure. The intermediate state in 25% HFA exhibits an enhanced a f f i n i t y towards the hydrophobic dye, ANS, and a native-like tryptophan fluorescence quenching. 1-D NMR spectra indicates loss of native-like tertiary fold as evident from the absence of ring current-shifted 'H resonances. CD, fluorescence, and NMR suggest that the transition from the native state to a molten globule state in 25% HFA is a cooperative process. A second structural transition from this compact molten globule-like state to an "open" helical state is observed at higher concentrations of HFA (250%). This transition is characterized by a dramatic loss of A N S binding with a concomitant increase in far UV CD bands. The thermal unfolding of the molten globule state in 25% HFA is sharply cooperative, indicating a predominant role of side-chain-side-chain interactions in the stability of the partially folded state. HID exchange experiments yield higher protection factors for many of the backbone amide protons from the four a-helices along with the C-terminal 3'0 helix, whereas little or no protection is observed for most of the amide protons from the triple-stranded antiparallel @-sheet domain. This equilibrium molten globule-like state of lysozyme in 25% HFA is remarkably similar to the molten globule state observed for a-lactalbumin and also with the molten globule state transiently observed in the kinetic refolding experiments of hen lysozyme. These results suggest that HFA may prove generally useful as a structure modifier in proteins.

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“…Further cases where an acid-induced molten globule may be functionally important include the role of the acidic chaperone protein, DnaJ, in stabilising re-folding rhodanese in a molten globule form [25], and the finding that the acid molten globule of retinol binding protein is the form which releases retinol [26]. These examples suggest that the cell may have its means of generating molten globules in order to regulate protein function and that the molten globules concerned are not restricted to monomeric species.…”

Section: R=hm;(v+h) Rtmentioning

confidence: 99%

Tumour necrosis factor is in equilibrium with a trimeric molten globule at low pH

Hlodan

Pain

1994

FEBS Letters

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The reversible acid denaturation of tumour necrosis factor, TNFa, a trimeric, all-p protein, leads to significant conformational changes within the molecule. A change in far UV CD spectra reveals a shift in the secondary structure content of the protein, with a-helical structure being induced. Loss of ellipticity in the near UV reflects a loss of tertiary interactions. This form of TNF is both compact and trimeric, as revealed by fluorescence anisotropy and sedimentation velocity analysis, respectively. Acid-denatured TNF therefore possesses the defining features of the molten globule intermediate while retaining the ability of the still incompletely folded monomers to exhibit the surface specificity necessary for maintaining the trhneric state.

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Retinol-binding protein is in the molten globule state at low pH

Cited by 141 publications

References 38 publications

Translational and Rotational Motions of Albumin Sensed by a Non-Covalent Associated Porphyrin Under Physiological and Acidic Conditions: A Fluorescence Correlation Spectroscopy and Time Resolved Anisotropy Study

Translational and Rotational Motions of Albumin Sensed by a Non-Covalent Associated Porphyrin Under Physiological and Acidic Conditions: A Fluorescence Correlation Spectroscopy and Time Resolved Anisotropy Study

Hexafluoroacetone hydrate as a structure modifier in proteins: Characterization of a molten globule state of hen egg‐white lysozyme

Tumour necrosis factor is in equilibrium with a trimeric molten globule at low pH

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