Privalov

P. L. Privalov, Physical Basis ofi the Stability ofi the Folded Conformations ofi Proteins Protein Folding, Freeman, New York, 1992 K. A. DiU, Biochemistry 29, 7133 (1990). 

Both attractive forces and repulsive forces are included in van der Waals interactions. The attractive forces are due primarily to instantaneous dipole-induced dipole interactions that arise because of fluctuations in the electron charge distributions of adjacent nonbonded atoms. Individual van der Waals interactions are weak ones (with stabilization energies of 4.0 to 1.2 kj/mol), but many such interactions occur in a typical protein, and, by sheer force of numbers, they can represent a significant contribution to the stability of a protein. Peter Privalov and George Makhatadze have shown that, for pancreatic ribonuclease A, hen egg white lysozyme, horse heart cytochrome c, and sperm whale myoglobin, van der Waals interactions between tightly packed groups in the interior of the protein are a major contribution to protein stability. 

Privalov, P. L., and Makhatadze, G. I., 1993. Contributions of hydration to protein folding thermodynamics. II. The entropy and Gibbs energy of hydration. y(9wra z/ of Molecular Biology 232 660-679. 

Menashi et al.153) could confirm the results of Privalov and Tiktopulo152 and inter-prete the described effects as follows In the case of native tropocollagen, the pyrrolidine residues are probably directed away from the fibrillar axis and are mostly coated by water which is structured in the immediate neighbourhood to the pyrrolidine residues. During the denaturation these pyrrolidine residues form hydrophobic bonds with each other or with other apolar residues within the same chain (endothermic interaction) while the structure of water breaks down (increase of entropy). 

Privalov et al (1989) studied the unfolded forms of several globular proteins [ribonuclease A, hen egg white lysozyme, apomyoglobin (apoMb), cytochrome c, and staphylococcal nuclease]. Unfolding was induced by 6 M Gdm-HCl at 10°C, heating to 80°C, or by low pH at 10°C with cross-links cleaved (reduction and carboxamidomethylation or removal of heme). The unfolded forms showed CD spectra (Fig. 27)... 

Privalov et al. (1989) also reported the temperature dependence of the ellipticity at 222 nm for the proteins studied at various pH values (Fig. 28). At the highest temperature studied (80°C), the 222 nm ellipticity value for the thermally unfolded, acid-unfolded, and Gdm-HCl-unfolded proteins appear to be converging, but show a range of 2000 deg cm2/dmol out of a total of 5000 deg cm2/dmol. (ApoMb is an exception in that, as noted before, the thermally denatured protein is apparently an associated /1-sheet. However, the acid- and Gdm HC1-unfolded forms of apoMb have similar [0] 222 values at 80°C.)... 

Fig. 28. Dependence of [9]222 of six proteins on pH at 10°C (left panels) and on temperature at the indicated pH (right panels). The states are indicated by solid, dotted, etc., lines as in Figure 27. The crossed symbol corresponds to data in the presence of 6 M GdmCl. From Privalov et al. (1989)./. Mol. Biol. 205, 737-750, with permission. 1989, Academic Press.

The CD of myoglobin at — 7°C, pH 3.72, indicates significant residual helix content, although by other criteria it is substantially unfolded (Privalov et al, 1986). 

Fig. 5. Partly folded states of apoMb formed in acid solution. The radius of gyration for each state is shown (data from Eliezer et at., 1995 Gast et al., 1994 Nishii et al., 1994), as is the population of secondary structure that develops during compaction (Barrick and Baldwin, 1993 Gilmanshin et al., 2001 data from Griko and Privalov, 1994). The helicity is expressed relative to that of holoMb.

Privalov, P.L. and S.J. Gill. 1988. Stability of protein structure and hydrophobic interaction. Adv Protein Chem 39 191-234. 

Privalov, P.L., N.N. Khechinashvili, and B.P. Atanasov. 1971. Thermodynamic analysis of thermal transitions in globular proteins. I. Calorimetric study of chy-motrypsinogen, ribonuclease and myoglobin. Biopolymers 10 1865-1890. 

Privalov, P.L. 1979. Stability of proteins small globular proteins. Adv Protein Chem 33 167-241. 

Privalov, P.L. and N.N. Khechinashvili. 1974. A thermodynamic approach to the problem of stabilization of globular protein structure a calorimetric study. J Mol Biol 86 665-684. 

Privalov, P.L. and S.A. Potekhin. 1986. Scanning microcalorimetry in studying temperature-induced changes in proteins. Methods Enzymol 131 4—51. 

Makhatadze, G.I., G.M. Clore, A.M. Gronenbom, and P.L. Privalov. 1994. Thermodynamics of unfolding of the all beta-sheet protein interleukin-1 beta. Biochemistry 33 9327-9332. 

Taylor, J.W., N.J. Greenfield, B. Wu, and P.L. Privalov. 1999. A calorimetric study of the folding-unfolding of an alpha-helix with covalently closed N- and C-terminal loops. J Mol Biol 291 965-976. 

Yu, Y., O.D. Monera, R.S. Hodges, and P.L. Privalov. 1996. Investigation of electrostatic interactions in two-stranded coiled-coils through residue shuffling. Biophys Chem 59 299-314. 

Privalov, G., V. Kavina, E. Freire, and P.L. Privalov. 1995. Precise scanning calorimeter for studying thermal properties of biological macromolecules in dilute solution. Anal Biochem 232 79-85. 

Stability of Proteins Proteins Which Do Not Present a Single Cooperative System P. L. Privalov... 

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