The relation of ion pairs to protein hydration: An IR spectroscopic and X‐ray crystallographic survey

Poole, P. L.; Barlow, D. J.

doi:10.1002/bip.360250212

Cited by 12 publications

(3 citation statements)

References 36 publications

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“…The lifetime of these interactions may be shorter than the lifetime of the interactions involved in the cooperative stabilization of secondary structures, but is long enough to induce internal and external conformational fluctuations of the protein (Frauenfelder & Gratton, 1986;Pace, 1986;Segawa & Kume, 1986). Recently peptide unit-2H20 interactions have been hypothesized to explain the amide I frequency of proteins (Jakobsen et al, 1986;Poole & Barlow, 1986; Castresana et al, 1987;Casal et al, 1988;Trewhella et al, 1989). The effects of direct peptide unit-ion interactions on protein conformations are less currently discussed (Schellman, 1987) although salt effects on the NH * N2H peptidic exchange have been demonstrated (Kim & Baldwin, 1982;Kim, 1986).…”

Section: Discussionmentioning

confidence: 99%

Conformational changes of Robinia pseudoacacia lectin related to modifications of the environment: FTIR investigation

Wantyghem¹,

Baron²,

Picquart³

et al. 1990

Biochemistry

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The secondary structural characteristics of one of the Robinia pseudoacacia lectins (RPA3) have been investigated by FTIR spectroscopy and have been established from absorption measurements in the amide I,I' frequency range and from the quantitative estimation of the rate of NH----N2H exchange. In an anhydrous state the protein structure consists mainly of antiparallel and parallel beta-structures, which represent 60% of the overall secondary structure of RPA3. Data obtained in different polar media (KBr, 2-chloroethanol, 2H2O, NaCl-2H2O and/or DPPC) reveal that RPA3 is a highly flexible protein. In pure 2H2O a rapid solvation of free peptide units and weak peripheral hydrogen bonds occurs, followed by the solvation of more internal parts of the lectin. The protein precipitates before total unfolding is reached. Increasing the ionic strength modifies the rate of NH----N2H exchange. NaCl concentrations of less than or equal to 0.15 M stabilize RPA3 in a structure close to that of the lyophilized lectin and diminish the rate of exchange, whereas higher NaCl concentrations partially disrupt the original secondary structure and increase the rate of exchange. Furthermore RPA3 was shown to interact with DPPC through polar interactions between the polar heads of the phospholipid and specific peptide units. These interactions appear to favor the NH----N2H exchange.

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Section: Discussionmentioning

confidence: 99%

Conformational changes of Robinia pseudoacacia lectin related to modifications of the environment: FTIR investigation

Wantyghem¹,

Baron²,

Picquart³

et al. 1990

Biochemistry

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“…Each domain is itself internally symmetrical, and stabilized by a hydrophobic core and a high degree of surface ion pairing (25,27,28). It has been proposed that these are the features primarily responsible for the remarkable thermal and chemical stability of yll-crystallin (23), which has been demonstrated in many studies (see refs.…”

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confidence: 97%

Binary liquid phase separation and critical phenomena in a protein/water solution.

Thomson

Schurtenberger²,

Thurston³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

253

226

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We have investigated the phase diagram of aqueous solutions of the bovine lens protein y1l-crystallin. For temperatures T < Tc = 278.5 K, we find that these solutions exhibit a reversible coexistence between two isotropic liquid phases differing in protein concentration. The dilute and concentrated branches of the coexistence curve were characterized, consistently, both by measurements of the two coexisting concentrations, c(T), and by measuring the cloud temperatures for various initial concentrations. The importance of studies of phase transitions in protein/ water solutions derives also from their physiological relevance to the supramolecular organization of normal tissues and to certain pathological states. For example, such phase transitions play an important role in the deformation of the erythrocyte in sickle-cell disease (4) and in the cryoprecipitation of immunoglobulins in cryoglobulinemia and rheumatoid arthritis (5, 6). Perhaps the most striking example is the involvement of liquid-liquid phase separation in the opacification of the ocular lens fiber cell cytoplasm in certain forms of mammalian cataracts (7-11). Our work has indicated (12, 13) that the phase separation of one class of lens proteins, the y-crystallins, may be the dominant mechanism responsible for the loss of transparency in such cataracts.Liquid-liquid phase separation in protein solutions has been studied by a number of investigators. Bungenberg de Jong (14) studied liquid-liquid phase separation extensively in a variety of colloidal systems, including aqueous protein solutions. He induced phase separation by the addition of simple electrolytes, polyelectrolytes, and organic solvents miscible with water. He regarded such phase separations as a subset of a broader phenomenon, which he termed coacervation. Dervichian (15) also studied liquid-liquid phase separation in aqueous protein solutions and constructed phase diagrams with which to represent his findings. Similar investigations continue to be reported. Most of these studies have been largely exploratory in character, with an emphasis on application to protein separation methods (16,17) and to microencapsulation (18,19) and on the qualitative classification of the effects of additives on the phase separations (14, 15). Relatively little work has been devoted to the study of phase separation in protein water solutions as a model system to investigate the basic statistical mechanics of critical phenomena and to examine the fundamental interaction energies acting between the constituent protein molecules. One notable exception has been the work of Ishimoto and Tanaka (20) and Tanaka, Nishio, and Sun (21), who studied phase separation in aqueous lysozyme solutions using light scattering methods.In this paper, we report our development of an experimental system that we believe will prove quite useful for the study of liquid-liquid phase separation and crystallization in protein solutions. The system comprises aqueous solutions of the bovine lens protein yl1-crystallin. The y...

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“…These proteins form rigid compact structures (Kuck, East & Yu, 1976;Yu, East, Chang & Kuck, 1977), having little surrounding free or bulk water (Racz, Tompa & Istavan, 1979;Blundell et al, 1981). 8-Crystallin, however, is predominantly a-helical (Kuck et al, 1976;Yu et al, 1977), and has a greater number of free acid groups (Poole & Barlow, 1986), properties which will tend to increase its attraction for water molecules, resulting in a protein that is more fluid. Thus, fluctuations of water in the environment might alter the interaction of the water molecules with the protein, leading to the type of space-group transition observed with the form II crystals.…”

Section: Resultsmentioning

confidence: 99%

Preliminary X-ray studies of adult turkey δ-crystallin: evidence of a space-group transition

Mylvaganam¹,

Slingsby²,

Lindley³

et al. 1987

Acta Crystallogr Sect B

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A new calcium-dependent crystal form of 6-crystallin grown at ambient temperatures using vapour-diffusion methods exhibits a temperature-dependent space-group transition. At lower temperatures the crystal form adopts space group P2t2~2 with Z = 2 and exhibits a diffraction pattern corresponding to the crystal form reported previously, while at 294 K the resulting space group is P2t2~2~ in which the e axis doubles to 140.2 (2)A with Z=4. A third crystal form which requires a higher concentration of calcium ions shows no such transition and appears to be remarkably stable to X-rays in comparison with the other crystal forms. These crystals diffract to at least 2-4 ~ in space group P212~2~ with Z = 4 and have the largest cell dimensions of the three crystal forms with a =88.9 (1), b = 144.8 (1) and ¢ = 152.5 (1) A.

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The relation of ion pairs to protein hydration: An IR spectroscopic and X‐ray crystallographic survey

Cited by 12 publications

References 36 publications

Conformational changes of Robinia pseudoacacia lectin related to modifications of the environment: FTIR investigation

Conformational changes of Robinia pseudoacacia lectin related to modifications of the environment: FTIR investigation

Binary liquid phase separation and critical phenomena in a protein/water solution.

Preliminary X-ray studies of adult turkey δ-crystallin: evidence of a space-group transition

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