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Independent of their localization in protein the hydrophobic amino acid residues have no effect on the molten globule state of apomyoglobin and the disulfide bond on the surface of apomyoglobin stabilizes this intermediate state.

Melnik TN, Majorina MA, Larina DS, Kashparov IA, Samatova EN, Glukhov AS, Melnik BS - PLoS ONE (2014)

Bottom Line: In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin.It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin.The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to "strengthen" the protein) can result in destabilization of the protein native state of apomyoglobin.

View Article: PubMed Central - PubMed

Affiliation: Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia.

ABSTRACT
At present it is unclear which interactions in proteins reveal the presence of intermediate states, their stability and formation rate. In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin. It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin. It has been shown also that introduction of a disulfide bond on the protein surface can stabilize the molten globule state. However in the case of apomyoglobin, stabilization of the intermediate state leads to relative destabilization of the native state of apomyoglobin. The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to "strengthen" the protein) can result in destabilization of the protein native state of apomyoglobin.

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Chevron plots.Chevron plot for wild type apomyoglobin WT (○) and its mutant form with the introduced SS-bond between amino acid residues 36 and 106 (H36C-F106C) (•).
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pone-0098645-g006: Chevron plots.Chevron plot for wild type apomyoglobin WT (○) and its mutant form with the introduced SS-bond between amino acid residues 36 and 106 (H36C-F106C) (•).

Mentions: Fig. 6 demonstrates a chevron plot for the wild-type apomyoglobin and its mutant form with the SS-bond between amino acid residues 36 and 106. It is seen that the SS-bond has affected both the folding branch and the unfolding branch of the plot. The folding branch of the chevron plot for apomyoglobin with the SS-bond has changed mainly due to stabilization of the molten globule state (Fig. 5). By using formulas, 1–3 (see Materials and Methods), one can estimate free energies of all states of apomyoglobin. However it is impossible to calculate the height of the energy barrier between the molten globule and unfolded states because protein transition from one state to the other takes less than 5 milliseconds and cannot be measured using the stopped-flow device (see Materials and Methods).


Independent of their localization in protein the hydrophobic amino acid residues have no effect on the molten globule state of apomyoglobin and the disulfide bond on the surface of apomyoglobin stabilizes this intermediate state.

Melnik TN, Majorina MA, Larina DS, Kashparov IA, Samatova EN, Glukhov AS, Melnik BS - PLoS ONE (2014)

Chevron plots.Chevron plot for wild type apomyoglobin WT (○) and its mutant form with the introduced SS-bond between amino acid residues 36 and 106 (H36C-F106C) (•).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043776&req=5

pone-0098645-g006: Chevron plots.Chevron plot for wild type apomyoglobin WT (○) and its mutant form with the introduced SS-bond between amino acid residues 36 and 106 (H36C-F106C) (•).
Mentions: Fig. 6 demonstrates a chevron plot for the wild-type apomyoglobin and its mutant form with the SS-bond between amino acid residues 36 and 106. It is seen that the SS-bond has affected both the folding branch and the unfolding branch of the plot. The folding branch of the chevron plot for apomyoglobin with the SS-bond has changed mainly due to stabilization of the molten globule state (Fig. 5). By using formulas, 1–3 (see Materials and Methods), one can estimate free energies of all states of apomyoglobin. However it is impossible to calculate the height of the energy barrier between the molten globule and unfolded states because protein transition from one state to the other takes less than 5 milliseconds and cannot be measured using the stopped-flow device (see Materials and Methods).

Bottom Line: In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin.It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin.The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to "strengthen" the protein) can result in destabilization of the protein native state of apomyoglobin.

View Article: PubMed Central - PubMed

Affiliation: Institute of Protein Research, RAS, Pushchino, Moscow Region, Russia.

ABSTRACT
At present it is unclear which interactions in proteins reveal the presence of intermediate states, their stability and formation rate. In this study, we have investigated the effect of substitutions of hydrophobic amino acid residues in the hydrophobic core of protein and on its surface on a molten globule type intermediate state of apomyoglobin. It has been found that independent of their localization in protein, substitutions of hydrophobic amino acid residues do not affect the stability of the molten globule state of apomyoglobin. It has been shown also that introduction of a disulfide bond on the protein surface can stabilize the molten globule state. However in the case of apomyoglobin, stabilization of the intermediate state leads to relative destabilization of the native state of apomyoglobin. The result obtained allows us not only to conclude which mutations can have an effect on the intermediate state of the molten globule type, but also explains why the introduction of a disulfide bond (which seems to "strengthen" the protein) can result in destabilization of the protein native state of apomyoglobin.

Show MeSH