Solvent denaturation of globular proteins Unfolding by the monoalkyl- and dialkyl-substituted formamides and ureas

Herskovits, Theodore T.; Behrens, Catherine Farenga; Siuta, Patricia B.; Pandolfelli, Emilia R.

doi:10.1016/0005-2795(77)90119-2

Cited by 30 publications

(10 citation statements)

References 20 publications

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“…According to Terwilliger and co-workers [29], the structure of the acellular Cardita hemoglobin revealed by electron microscopy exhibits a structural similarity with molluscan hemocyanin. The unfolding profiles of LtHb and ArHb, similar to other globular shaped hemoglobin molecules [30,31], have unfolding midpoints ranging from 4.5 to 5.4 M urea at 37 C. Unfolding is followed by changes in the Soret wavelength maximum wherein the decrease in absorbance is directly associated with greater heme exposure to the solvent as the urea concentration is increased. Earlier light scattering studies indicated that LtHb does not undergo subunit dissociation as a function of decreasing concentration in contrast to human and bovine hemoglobins, which undergo subunit dissociation to dimers as their concentrations are decreased [17].…”

Section: Resultsmentioning

confidence: 98%

Acellular Invertebrate Hemoglobins as Model Therapeutic Oxygen Carriers: Unique Redox Potentials

Harrington

Kobayashi

Dorman

et al. 2007

Artificial Cells, Blood Substitutes, and Biotechnology

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Natural acellular polymeric hemoglobins (Hb) provide oxygen transport and delivery within many terrestrial and marine invertebrate organisms. It has been our premise that these natural acellular Hbs may serve as models of therapeutic hemoglobin-based oxygen carriers (HBOC). Our attention has focused on the acellular Hb from the terrestrial invertebrate, Lumbricus terrestris (Lt), which possesses a unique hierarchical structure and a unique ability to function extracellularly without oxidative damage. Lumbricus Hb and Arenicola Hb are resistant to autoxidation, chemical oxidation by potassium ferricyanide, and have little or no capacity to transfer electrons to Fe(+3)-complexes at 37 degrees C. An understanding of how these invertebrate acellular oxygen carriers maintain their structural integrity and redox stability in vivo is vital for the design of a safe and effective red cell substitute. We report here a positive redox potential for these giant hemoglobins that may lie at the basis for its resistance to oxidation.

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Section: Resultsmentioning

confidence: 98%

Acellular Invertebrate Hemoglobins as Model Therapeutic Oxygen Carriers: Unique Redox Potentials

Harrington

Kobayashi

Dorman

et al. 2007

Artificial Cells, Blood Substitutes, and Biotechnology

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“…Therefore, organic solvents may enhance the disassembly of tetrameric insulin into monomers, as compared with water. In addition, the interaction between the protein and organic solvents solvates peptide backbone, thereby denaturing the native structure of the protein (58). As the protons of the amide group are substituted for methyl groups, the hydrogen-bond interactions between the protein and organic solvent will most likely be reduced.…”

Section: Structural Conversion Of B11-b17 Core Residues From A-helix mentioning

confidence: 99%

“…Intermolecular interactions between water and formamide have been studied as a model system to mimic the hydration of a protein, because the functional group of formamide can represent the peptide backbone (57). When formamide is directly added to a protein solution, globular proteins are reported to unfold (58,59). Previous studies (60,61) have demonstrated that both the polar and nonpolar functional groups of formamide and its methyl derivatives (Scheme 1) contribute to the denaturation of globular proteins.…”

Section: Introductionmentioning

confidence: 99%

Amyloid Fibrillation of Insulin under Water-Limited Conditions

Choi

Lee

Jin

et al. 2014

Biophysical Journal

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Amyloid fibrillation in water-organic mixtures has been widely studied to understand the effect of protein-solvent interactions on the fibrillation process. In this study, we monitored insulin fibrillation in formamide and its methyl derivatives (formamide, N-methyl formamide, N,N-dimethyl formamide) in the presence and absence of water. These model solvent systems mimic the cellular environment by providing denaturing conditions and a hydrophobic environment with limited water content. Thioflavin T (ThT) assay revealed that binary mixtures of water with formamide and its methyl derivatives enhanced fibrillation rates and ?-sheet abundance, whereas organic solvents suppressed insulin fibrillation. We utilized solution small-angle x-ray scattering (SAXS) and differential scanning calorimetry (DSC) to investigate the correlation between protein-solvent interactions and insulin fibrillation. SAXS experiments combined with simulated annealing of the protein indicated that the degree of denaturation of the hydrophobic core region at residues B11-B17 determines the fibrillation rate. In addition, DSC experiments suggested a crucial role of hydrophobic interactions in the fibrillation process. These results imply that an environment with limited water, which imitates a lipid membrane system, accelerates protein denaturation and the formation of intermolecular hydrophobic interactions during amyloid fibrillation.

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“…Herskovits et a1 [32] have measured unfolding of globular proteins by monoalkyland dialkyl-substituted formamides and ureas. There does not appear to be a direct correlation between the effectiveness of these compounds as inducers of differentiation and their ability to unfold proteins as estimated by solvent denaturation midpoints.…”

Section: Levermentioning

confidence: 99%

Regulation of dome formation in differentiated epithelial cell cultures

Lever

1979

J Supramol Struct

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Rat mammary (Rama 25) and dog kidney (MDCK) epithelial cell cultures formed 'domes' of cells due to fluid accumulation in focal regions between the culture dish and the cell monolayer. Addition of ouabain caused collapse of domes, suggesting that transport functions were required for maintenance of domes. Dome formation in both epithelial cell lines was stimulated by a broad spectrum of known inducers of erythroid differentiation in Fried erythroleukemia cells. Among these inducers were: 1) polar solvents such as dimethyl-sulfoxide, dimethylformamide, and hexamethylene bisacetamide; 2) purines such as hypoxanthine, inosine, and adenosine; 3) low-molecular-weight fatty acids such as n-butyrate; and 4) conditions expected to elevate levels of cyclic AMP. In the latter group were activators of adenylate cyclase such as cholera toxin and prostaglandin E 1; cyclic AMP phosphodiesterase inhibitors such as theophylline and 1-methyl-3-isobutylxanthine; and analogs of cyclic AMP. Induction of domes occurred 15--30 h after addition of inducer to the culture medium. Induction by chemicals was serum-dependent and required protein synthesis but not DNA synthesis. Induced dome formation was reversible after removal of inducer, requiring the continuous presence of inducer. Reversal was also observed after either either removal of serum or addition of inhibitors of protein synthesis. These results suggest that hypothesis that domes arise in these epithelial cultures by a process that is similar to cell differentiation and is influenced by cyclic AMP.

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Solvent denaturation of globular proteins Unfolding by the monoalkyl- and dialkyl-substituted formamides and ureas

Cited by 30 publications

References 20 publications

Acellular Invertebrate Hemoglobins as Model Therapeutic Oxygen Carriers: Unique Redox Potentials

Acellular Invertebrate Hemoglobins as Model Therapeutic Oxygen Carriers: Unique Redox Potentials

Amyloid Fibrillation of Insulin under Water-Limited Conditions

Regulation of dome formation in differentiated epithelial cell cultures

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