Dynamic equilibrium unfolding pathway of human tumor necrosis factor-α induced by guanidine hydrochloride

Kim, Yong Rok; Hahn, Joong Sik; Hong, Heedeok; Jeong, Woojin; Song, Nam Woong; Shin, Hang Cheol; Kim, Dongho

doi:10.1016/s0167-4838(98)00263-5

Cited by 7 publications

(5 citation statements)

References 30 publications

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“…The fast rotation of the tryptophan side chains, which has a correlation time in the range of 50-400 ps (in comparison to 30 ps for free L-tryptophan), does not always exist in native proteins (59,76,77). In our case, no such motion was seen in the native and molten globule states.…”

Section: Discussioncontrasting

confidence: 59%

Structure and Dynamics of the α-Lactalbumin Molten Globule: Fluorescence Studies Using Proteins Containing a Single Tryptophan Residue

et al. 2001

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The fluorescence properties of three variants of alpha-lactalbumin (alpha-LA) containing a single tryptophan residue were investigated under native, molten globule, and unfolded conditions. These proteins have levels of secondary structure and stability similar to those of the wild type. The fluorescence signal in the native state is dominated by that of W104, with the signal of W60 and W118 significantly quenched by the disulfide bonds in their vicinity. In the molten globule state, the magnitude of the fluorescence signal of W60 and W118 increases, due to the loss of rigid, specific side chain packing. In contrast, the magnitude of the signal of W104 decreases in the molten globule state, perhaps due to the protonation of H107 or quenching by D102 or K108. The solvent accessibilities of individual tryptophan residues were investigated by their fluorescence emission maximum and by acrylamide quenching studies. In the native state, the order of solvent accessibility is as follows: W118 > W60 > W104. This order changes to W60 > W104 > W118 in the molten globule state. Remarkably, the solvent accessibility of W118 in the alpha-LA molten globule is lower than that in the native state. The dynamic properties of the three tryptophan residues were examined by time-resolved fluorescence anisotropy decay studies. The overall rotation of the molecule can be observed in both the native and molten globule states. In the molten globule state, there is an increase in the extent of local backbone fluctuations with respect to the native state. However, the fluctuation is not sufficient to result in complete motional averaging. The three tryptophan residues in the native and molten globule states have different degrees of motional freedom, reflecting the folding pattern and dynamic heterogeneity of these states. Taken together, these studies provide new insight into the structure and dynamics of the alpha-LA molten globule, which serves as a prototype for partially folded proteins.

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Section: Discussioncontrasting

confidence: 59%

Structure and Dynamics of the α-Lactalbumin Molten Globule: Fluorescence Studies Using Proteins Containing a Single Tryptophan Residue

et al. 2001

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“…To understand which relaxation process is dominant, one may refer to data obtained for other Trp-containing macromolecules. Table 3 demonstrates that a relaxation process with a time of 4∼6 ns is quite typical for unfolded proteins (3,32,45,46), adrenocorticotropic hormones (47), and synthetic polypeptides (48,49). Note that this "slow" motion seems nearly independent of amino acid sequence.…”

Section: Resultsmentioning

confidence: 92%

Nanosecond Dynamics of Tryptophans in Different Conformational States of Apomyoglobin Proteins

2000

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Fluorescence anisotropy kinetics were employed to quantify the nanosecond mobility of tryptophan residues in different conformational states (native, molten globule, unfolded) of apomyoglobins. Of particular interest is the similarity between the fluorescence anisotropy decays of tryptophans in the native and molten globule states. We find that, in these compact states, tryptophan residues rotate rapidly within a cone of semiangle 22-25 degrees and a correlation time of 0.5 ns, in addition to rotating together with the whole protein with a correlation time of 7-11 ns. The similar nanosecond dynamics of tryptophan residues in both states suggests that the conformation changes that distinguish the molten globule and native states of apomyoglobins originate from either subtle, slow rearrangements or fast changes distant from these tryptophans.

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“…The fittings for both isotropic and anisotropic decays were performed by a least-squares deconvolution fitting process. The vertical and horizontal components of fluorescence emission were simultaneously fitted to extract the anisotropy decay functions, using the LIFETIME program with an iterative nonlinear least-squares deconvolution procedure that was developed at the University of Pennsylvania …”

Section: Methodsmentioning

confidence: 99%

Directly meso−meso Linked Porphyrin Rings: Synthesis, Characterization, and Efficient Excitation Energy Hopping

et al. 2004

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Directly meso-meso linked porphyrin rings CZ4, CZ6, and CZ8 that respectively comprise four, six, and eight porphyrins have been synthesized in a stepwise manner from a 5,10-diaryl zinc(II) porphyrin building block. Symmetric cyclic structures have been indicated by their very simple (1)H NMR spectra that exhibit only a single set of porphyrin and their absorption spectra that display a characteristic broad nonsplit Soret band around 460 nm. Energy minimized structures calculated at the B3LYP/6-31G* level indicate that a dihedral angle between neighboring porphyrins decreases in order of CZ6 > CZ8 > CZ4, which is consistent with the (1)H NMR data. Photophysical properties of these molecules have been examined by the steady-state absorption, fluorescence, fluorescence lifetime, fluorescence anisotropy decay, and transient absorption measurements. Both the pump-power dependence on the femtosecond transient absorption and the transient absorption anisotropy decay profiles are directly related with the excitation energy migration processes within the porphyrin rings, where the exciton-exciton annihilation time and the polarization anisotropy rise time are well described in terms of the Forster-type incoherent energy hopping model. Consequently, the excitation energy hopping rates have been estimated for CZ4 (119 +/- 2 fs)(-)(1), CZ6 (342 +/- 59 fs)(-)(1), and CZ8 (236 +/- 31 fs)(-)(1), which reflect the magnitude of the electronic coupling between the neighboring porphyrins. Overall, these porphyrin rings serve as a well-defined wheel-shaped light harvesting antenna model in light of very efficient excitation energy hopping along the ring.

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Dynamic equilibrium unfolding pathway of human tumor necrosis factor-α induced by guanidine hydrochloride

Cited by 7 publications

References 30 publications

Structure and Dynamics of the α-Lactalbumin Molten Globule: Fluorescence Studies Using Proteins Containing a Single Tryptophan Residue

Structure and Dynamics of the α-Lactalbumin Molten Globule: Fluorescence Studies Using Proteins Containing a Single Tryptophan Residue

Nanosecond Dynamics of Tryptophans in Different Conformational States of Apomyoglobin Proteins

Directly meso−meso Linked Porphyrin Rings: Synthesis, Characterization, and Efficient Excitation Energy Hopping

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