Spin labels in membranes problems in practice

Schreier, Shirley; Polnaszek, Carl F.; Smith, Ian C. P.

doi:10.1016/0304-4157(78)90011-4

Cited by 368 publications

(200 citation statements)

References 124 publications

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“…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).…”

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confidence: 99%

“…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).…”

mentioning

confidence: 99%

“…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 host lipids.…”

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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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confidence: 99%

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confidence: 99%

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confidence: 99%

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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 order parameter decreased linearly with the increasing A 1 for S > 0.1 and A 1 < 1.1 mT (Gaffney, 1976). At S < 0.1 and A!> 1.1 mT the spin label motion was nearly isotropic and its rate of molecular reorientation could be described by rotational correlation time i calculated by Schreier et al (1978) (Kolena, 1976 (Kolena and Channing, 1985), estradiol (Kolena et al, 1977) and testosterone (&Scaron;ebökovâ and Kolena, 1978) concentrations-in plasma and ovarian membranes. Cholesterol was assayed enzymatically (Sate, 1984).…”

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confidence: 99%