Molecular interactions in mixed lecithin systems

Phillips, Michael C.; Ladbrooke, B.D.; Chapman, D.

doi:10.1016/0005-2736(70)90163-x

Cited by 295 publications

(115 citation statements)

References 10 publications

Supporting

Mentioning

101

Contrasting

Unclassified

Order By: Relevance

“…2). In addition, also shown in Figure 3, The thermal response of simple, artifical lipid systems is modulated in part by the degree of unsaturation of the fatty acids of the component lipids (20). On this basis, the high proportion of unsaturated fatty acid in the cauliflower plasma membrane (Table II) would be consistent with the absence of a thermal transition above 0°C.…”

Section: Methodsmentioning

confidence: 79%

Thermal Behavior and Lipid Composition of Cauliflower Plasma Membranes in Relation to ATPase Activity and Chilling Sensitivity

Wright¹,

McMurchie²,

Pomeroy³

et al. 1982

Plant Physiol.

View full text Add to dashboard Cite

A plasma-membrane fraction rich in ion-stimulated ATPase activity was isolated from cauliflower (Brassica olerwea L.) buds. The activity of the ATPase was dependent on Mg2" and stimulated 4-fold by KV. The lipids of the membrane fraction contained 57% by weight of phospholipid, 16% glycolipid including sterol glycosides, and 27% neutral lipids. Sterols and sterol esters comprised 9% by weight of the total lipid fraction, and the M ratio of total sterol to phospholipid was 0.5. Fatty acid unsaturation of the membrane lipids was 75%. Arrhenius plots of the Mg2+ and Mg2e + K+ stimulated ATPase activity were biphasic with an increase in activation energy occurring below about 12°C, a response typical of some membraneassociated enzymes of chilling-sensitive plants. No thermal transitions were detected in the membranes or membrane lipids between 0 and 30°C using differential scanning calorimetry and electron spin resonance spectroscopy. This type of thermal behavior is typical of membranes of chillingresistant plants. It was concluded that the low temperature increase in activation energy of the ion-stimulated, membrane-associated ATPase is an intrinsic property of the enzyme system and not the result of a transition in the bulk membrane lipid.Many membrane-bound enzymes associated with mitochondria and chloroplasts of chilling-sensitive plants show nonlinear Ar-rhenius plots with an increase in Ea' below about 10°C (12,23 23) and together they provide a molecular explanation of chilling injury (12). Some soluble enzymes also exhibit nonlinear Arrhenius plots at low temperatures. This can be explained on the basis of a direct, temperature-induced, reversible alteration in the tertiary structure of the enzyme or the enzyme-substrate complex (4). Examples from plants include some key enzymes of carbon metabolism, such as P-enolpyruvate carboxylase (7), but the role of these enzymes in the development of chilling injury has yet to be elucidated. Furthermore, some membrane-associated enzymes from chilling-resistant plants also exhibit nonlinear Arrhenius plots, e.g. the photoreduction of DCIP by chloroplasts from barley (17) and pea (18), assayed in the presence ofuncouplers. However, no phase separation (21) or change in lipid ordering (24) occurs in the membranes of these plants at temperatures coincident with the altered activation energies and such changes are more likely a direct effect of temperature on the uncoupler-enzyme-substrate complex. Inasmuch as growth of barley and pea continue well into the chilling temperature range, the altered enzyme kinetics observed in vitro at chilling temperatures have little influence on growth and development of these plants. These observations stress the importance of establishing whether tissue metabolism reflects the altered kinetics of the isolated enzyme systems before such changes are causally linked to chilling injury.The question of the relative contribution of changes in enzyme kinetics and/or changes in membrane lipid order to chilling injury is complicated with...

show abstract

Section: Methodsmentioning

confidence: 79%

Thermal Behavior and Lipid Composition of Cauliflower Plasma Membranes in Relation to ATPase Activity and Chilling Sensitivity

Wright¹,

McMurchie²,

Pomeroy³

et al. 1982

Plant Physiol.

View full text Add to dashboard Cite

show abstract

“…Fig. 3 gives the results of experiments with liposomes prepared from various saturated leeithins and from some mixtures exhibiting only a single phase transition because of cocrystallization [18][19][20]. Since the light scattering of liposome suspensions changes abruptly on passing the T c [21,22], this criterion could be used to determine the temperature region where the phase transition occurs.…”

Section: Resultsmentioning

confidence: 99%

The effect of chain length and lipid phase transitions on the selective permeability properties of liposomes

Blok

Neut-Kok

Deenen

et al. 1975

Biochimica et Biophysica Acta (BBA) - Biomembranes

279

View full text Add to dashboard Cite

show abstract

“…Finally, the temperature-composition phase diagrams for lateral phase separations of two-component pure lipid systems can be determined by use of spin-label techniques (13,14) as well as calorimetric methods (15). Freeze-fracture electron micrographs of binary phospholipid mixtures (16,17) and biological membranes (18)(19)(20) sometimes show zones and/or "particle free" patches that may be due to lateral phase separations of the type considered here.…”

mentioning

confidence: 96%

Lateral Phase Separations in Membrane Lipids and the Mechanism of Sugar Transport in Escherichia coli

Linden

Wright²,

McConnell³

et al. 1973

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

305

149

View full text Add to dashboard Cite

Changes in slope of Arrhenius plots for transport can, in some instances, be detected at two different temperatures for cells that have a relatively simple fatty-acid composition in the membrane lipids. These characteristic temperatures correlate with the characteristic temperatures that define changes of state in membrane phospholipids as revealed by the paramagnetic resonance of the spin label TEMPO (2,2,6,6-tetramethylpiperidine-l-oxyl). The higher of these characteristic temperatures is that at which the formation of solid patches of membrane lipids is first detected. The lower is the end point of the course of lateral phase separations, at which all the membrane lipids are in a solid phase. For cells enriched for elaidic acid, the rate of transport increases by as much as 2-fold as the temperature is decreased by less than 10, at the higher characteristic temperature. At this characteristic temperature, lateral phase separations begin in the membrane phospholipids. This is also the temperature where one predicts a striking increase in the lateral compressibility of the membrane lipids. These data are thus interpreted to indicate that a component of the transport system vertically penetrates one or both monolayer faces of the membrane during transport, or that some other event involving the lateral compression of the phospholipids is important for transport.Essential fatty-acid auxotrophs of Escherichia coli are powerful tools that have been exploited to study the influence of lipid physical properties on the function and assembly of cellular membranes (1-7). Arrhenius plots for transport have been shown to have a biphasic shape, and the characteristic temperature that defines the change in slope in these plots is exquisitely responsive to the physical characteristics of the essential fatty-acid supplement present during cellular growth. The characteristic temperatures reflect the melting characteristics of the essential fatty-acid supplement, e.g., the characteristic temperatures are in decreasing order when determined in cells grown in media supplemented with fatty acids that are trans-monoenoic, cis-monoenoic, and cis, cisdienoic (or cis, cis, cis-trienoic), (2-4, 6). The first strong indications that the characteristic temperatures correspond to a change of state in the membrane lipids came from two independent studies: (1) The characteristic temperatures for two unrelated transport systems were identical for cells grown with a single essential fatty acid (2, 4). (2) A change in state detected in a monolayer of phosphatidylethaAbbreviations: T is the absolute temperature (degrees Kelvin), th and tI refer to "higher" and "lower" characteristic temperatures (0C) as revealed by spin labeling (or other physical techniques), and th* and tt* refer to the higher and lower temperatures (0C) as revealed by transport rate. The spin label TEMPO is 2,2,6,6-tetramethylpiperidine-1-oxyl. MATERIALS AND METHODSGrowth and Properties of Bacterial Strains. Strain 30E,3ox-was used exclusively in the studies reporte...

show abstract

Molecular interactions in mixed lecithin systems

Cited by 295 publications

References 10 publications

Thermal Behavior and Lipid Composition of Cauliflower Plasma Membranes in Relation to ATPase Activity and Chilling Sensitivity

Thermal Behavior and Lipid Composition of Cauliflower Plasma Membranes in Relation to ATPase Activity and Chilling Sensitivity

The effect of chain length and lipid phase transitions on the selective permeability properties of liposomes

Lateral Phase Separations in Membrane Lipids and the Mechanism of Sugar Transport in Escherichia coli

Contact Info

Product

Resources

About