Thermodynamics and membrane processes

Klein, Roger A.

doi:10.1017/s0033583500003772

Cited by 29 publications

(6 citation statements)

References 257 publications

(263 reference statements)

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“…This conclusion is supported by the lack of a significant shift in the transition temperature determined by the intersect of two lines fitted to a decreasing number of data points (Fig. 3) and by the thermodynamic properties obtained when data are analyzed as a curvilinear function based on the equation described by Klein (10). When this equation is used it is possible to determine the transition midpoint (Tm), the transition width (Tw), the partition ratio (P) for label in the fluid and solid phases, as well as the enthalpy and entropy for motion where X is the jump frequency; R, the universal gas constant (8.34 J°K7'); k, the rate constant; AHf, AHl, ASf, and AS, the enthalpy and entropy in the fluid and solid phases, respectively; Tm the transition midpoint ('K); Tw the width at half-height of the transition (°K); P the ratio of the label in the fluid and solid phases.…”

Section: Discussionmentioning

confidence: 73%

“…1) that a thermotropic transition occurs in plant polar lipids the application of this model, in preference to other models described by Klein (10), seemed appropriate. Klein (10) has shown that the distribution of the Arrhenius plot in relation to the transition temperature is determined by P. We have therefore determined a value ofP for a nitroxide spin label in relatively defined systems, (18) consisting of either pure DPPC or mixtures of DPPC and polar lipids from wheat roots. As shown in Table I, the value obtained for P using DPPC is 0.2 and the distribution of the Arrhenius plot, shown in Figure 4A is consistent with a melting transition at 41C and a transition width of 2 C deg.…”

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confidence: 99%

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Phase Transitions in Thylakoid Polar Lipids of Chilling-Sensitive Plants

Raison

Orr²

1986

Plant Physiol.

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The phase behavior of thylakoid polar lipids from plants sensitive to chiling injury was investigated by calorimetry, electron spin resonance spectroscopy of spin labels, and fluorescence intensity after labeling with trans-parinaric acid. The plants used were oleander (Nerium olader), mung bean (Vigna radiata L. var Mungo), and tomato (Lycopersicon esculentum cv Grosse Lisse). For all plants the initiation temperature for the calorimetric exotherm was coincident (±1lC) with the transition determined by the increase in the temperature coefficient of spin label motion and fluorescence intensity of trans-parinaric acid. For oleander plants, grown at 45°C, the transition was at 7°C while for plants from the same clone, grown at 20°C, it was at -2°C. For mung bean and tomato the transition was between 9 and 12°C. The similarity in the transition detected by spin labeling and fluorescence intensity suggest that spin labels, like the fluorescent label traws-parinaric acid, preferentially partition into domains of ordered lipid. The coincidence of the temperature for initiation of the transition, determined by the three techniques, shows that each is a valid method of assessing a phase transition in membrane polar lipids.It has been proposed that chilling-injury is initiated by a thermally-induced transition in the structure or phase state of some ofthe lipids which constitute the bilayers ofcell membranes (11,12,23). Evidence supporting this hypothesis has relied mainly on the correlation between the critical temperature below which the plant is injured and the temperature of the lipid phase transition detected indirectly using either spin (21, 22) or fluorescent (24) probes.This explanation of the primary cause of chilling injury has not been universally accepted. The principal objection is that the phase transition is inferred from a change in the temperature coefficient of motion ofa spin probe (28) intercalated with either mitochondria or chloroplast membranes or liposomes formed from the lipids of these membranes (6,22). Furthermore, this inference relating the change in the temperature coefficient of probe motion to a phase transition has been criticized on the grounds that probes can form impurity pools within the host lipids and have the potential to perturb the system being analyzed (3,28). In addition, motion ofthe spin probe is usually calculated using an equation which depends on the probe undergoing isotropic motion (9) but it has been noted that motion of the nitroxide-type probes, commonly used in these studies with membrane lipids, is rarely isotropic (28). Thus, the motion parameter calculated from the electron spin resonance spectra of probes in membrane lipids could represent the summation of segmental, diffusion, and vibrational motion as well as a component influenced by the ordering ofthe probe in the membrane lipids (28). Under these conditions the motion parameter could increase markedly as membrane lipids become more ordered at low temperature even though no transition occurred in the ...

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Section: Discussionmentioning

confidence: 73%

mentioning

confidence: 99%

Phase Transitions in Thylakoid Polar Lipids of Chilling-Sensitive Plants

Raison

Orr²

1986

Plant Physiol.

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“…A two-state transition model rests on the assumption that the initial and final states have measurably different thermodynamic properties (22). To unambiguously characterize these states via infrared spectroscopy, they must also have measurably different spectral characteristics.…”

Section: Resultsmentioning

confidence: 99%

Characterization of cooperative conformational transitions by Fourier transform infrared spectroscopy: application to phospholipid binary mixtures

Dluhy¹,

Moffatt²,

Cameron³

et al. 1985

Can. J. Chem.

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Temperature-induced cooperative conformational transitions in biopolymers may be examined in aqueous solution by the use of Fourier transform infrared spectroscopy. The transition is described in terms of a two-state model with a fractional population parameter (which describes the degree of transition at various values intermediate between the two limiting cases) that can be generated by a least-squares technique. This procedure allows for calculation of a conformational index without assuming a linear dependence of the infrared parameter on the extent of transition. Calculations based on the Zimm-Bragg theory of cooperative conformational transitions allow thermodynamic quantities to be derived using the conformational index in conjunction with calorimetric measurements.The method is illustrated with data from the gel/liquid-crystalline phase transitions of binary phospholipid vesicles where the use of isotopic substitution allows the conformation of each component of the binary mixture to be independently monitored. The data suggest the coexistence of well-defined structural domains of phospholipid as well as the preferential clustering of one of the lipid components at the interface between the two phases. On peut Ctudier les transitions conformationnelles coopCratives induites par la tempirature des biopolymkres en solution aqueuse en faisant appel B la spectroscopie infrarouge par transformation de Fourier. On peut dCcrire la transition en fonction d'un modkle a deux Ctats avec un paramktre de population fractionnaire (qui dtcrit le degrC de transition des diverses valeurs intermkdiaires entre les deux cas limites) que I'on peut gCnCrC par la technique des moindres c a d s . Ce procCdC permet de calculer un indice conformationnel sans faire I'hypothkse qu'il existe une relation linkaire entre le paramktre infrarouge et le degri de transition. Des calculs basks sur la thtorie de Zimm-Bragg des transitions conformationnelles coopCratives permettent dlCvaluer des quantitks thermodynamiques a l'aide de l'indice conformationnel couplC a des mesures calorimCtriques.On illustre la mCthode avec des donnees provenant de transitions de phases gel/liquide cristallin de vCsicules de phospholipides binaires oij I'utilisation de la substitution isotopique permet de determiner d'une manikre indkpendante la conformation de chacun des composants du mClange binaire. Les donnCes suggkrent qu'il y a une coexistence de domaines structuraux de phospholipides bien dCfinis ainsi qu'une aggregation prCfCrentielle de I'un des lipides composants a l'interface entre les deux phases.[Traduit par le journal]

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“…1973) around the equilibrium. In a rate process the controlling unit is a stable nucleus (which reaches the point of no return and transits into the other phase) (Klein, 1982). It is not obvious what determines the size of the nucleus.…”

Section: Discussionmentioning

confidence: 99%

Electrical Double Layers in Biology

Blank¹

1986

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Thermodynamics and membrane processes

Cited by 29 publications

References 257 publications

Phase Transitions in Thylakoid Polar Lipids of Chilling-Sensitive Plants

Phase Transitions in Thylakoid Polar Lipids of Chilling-Sensitive Plants

Characterization of cooperative conformational transitions by Fourier transform infrared spectroscopy: application to phospholipid binary mixtures

Electrical Double Layers in Biology

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