The effect of calcium on temperature-induced phase changes in liquid-crystalline cardiolipin structure

Hegner, D.; Schummer, Ulrich; Schnepel, G.H.

doi:10.1016/0005-2736(73)90291-5

Cited by 30 publications

(6 citation statements)

References 19 publications

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“…This indicates that negatively charged DPG provides a binding site for paramagnetic metal ions which enhances the dipolar interaction. These results are consistent with the binding of divalent cations to negatively charged lipids such as DPG (Hegner et al, 1973) and phosphatidylglycerol (Wagner et al, 1980).…”

Section: Resultssupporting

confidence: 87%

Distance estimate of the active center of D-.beta.-hydroxybutyrate dehydrogenase from the membrane surface

La¹,

Jo²,

Fleischer³

1987

Biochemistry

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D-beta-Hydroxybutyrate dehydrogenase (EC 1.1.1.30) is a membrane-bound, lipid-requiring enzyme which has a reactive sulfhydryl in the vicinity of the active center. The spin-probe-spin-label technique has been used to estimate the distance of separation of the reactive sulfhydryl of D-beta-hydroxybutyrate dehydrogenase from the bilayer surface. The reactive sulfhydryl of the enzyme was derivatized with the maleimide spin-label reagent 4-maleimido-2,2,6,6-tetramethylpiperidinyl-1-oxy in the presence of the cofactor NAD+. The derivatized enzyme, inserted (inlaid orientation) into phospholipid vesicles, was titrated with spin probes, either Mn2+ or Gd3+, until the spin-label EPR spectrum was reduced in amplitude to its residual (limiting) value. From this limiting amplitude, the dipolar interaction coefficient was obtained, which is related to the reciprocal of the distance to the sixth power. The radial distances of closest approach of the paramagnetic Mn2+ and Gd3+ ions to the spin-label nitroxide on the enzyme were found to be 18 and 16 A, respectively. These calculated distances were in accord with those determined by comparison with a phosphatidylcholine calibration system having 2,2-dimethyloxazolidinyl-1-oxy spin-labels located at selected positions along the sn-2 fatty acyl chain. Since the distal nitroxide moiety of the maleimide spin-label (17 A from the bilayer surface) is 8 A from the sulfhydryl addition site, the two limiting distances of immersion of the reactive sulfhydryl within the bilayer are 9 and 25 A. The shorter distance is considered more compatible with facile access of the coenzyme to the active site of the enzyme.

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Section: Resultssupporting

confidence: 87%

Distance estimate of the active center of D-.beta.-hydroxybutyrate dehydrogenase from the membrane surface

La¹,

Jo²,

Fleischer³

1987

Biochemistry

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“…In particular, we have to envisage two principally different possibilities: Ca z+ and(or) Mg 2 § which we use for contraction and expansion of nuclear membranes, affects the lipids either directly or indirectly, i.e., via an expansion or contraction of membrane proteins. The first possibility would be in line with findings showing that Ca 2 § is known to rigidify model membranes containing high concentrations of negatively charged phospholipids such as cardiolipin (16) or PS (30) or binary liposomes of PC-PS (27,29). This Ca effect is generally ascribed to a Ca-induced isothermic lipid phase transition coupled with a separation of the fluid from the ordered lipids (27,29,30).…”

Section: Possible Role Of the Nuclear Matrix In The Modulation Of Nuclear Membrane Lipid Fluiditysupporting

confidence: 54%

Expansion and apparent fluidity decrease of nuclear membranes induced by low Ca/Mg. Modulation of nuclear membrane lipid fluidity by the membrane-associated nuclear matrix proteins?

Wunderlich¹,

Giese²,

Bucherer³

1978

The Journal of Cell Biology

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Macronuclei isolated from Tetrahymena are contracted in form (average diameter:10.2 /.tm) at a final Ca/Mg (3:2)concentration of 5 raM. Lowering the ion concentration to 1 mM induces an expansion of the average nuclear diameter to 12.2/xm. Both contracted and expanded nuclei are surrounded by a largely intact nuclear envelope as revealed by thin-sectioning electron microscopy. Nuclear swelling is accompanied by an expansion of the nuclear envelope as indicated by the decrease in the frequency of nuclear pore complexes from 52.6 to 42.1 pores/ /zm ~ determined by freeze-etch electron microscopy. Contracted nuclear membranes reveal particle-devoid areas (average size: 0.21 /xm 2) on 59% of their fracture faces at the optimal growth temperature of 28~ About three-fifths of the number of these smooth areas disappear upon nuclear membrane expansion. Electron spin resonance using 5-doxylstearic acid as a spin label indicates a higher lipid fluidity in contracted than in expanded nuclear membranes. Moreover, a thermotropic lipid clustering occurs at -17~ only in expanded nuclear membranes. In contrast to the nuclear membrane-bound lipids, free lipids extracted from the nuclei rigidify with increasing Ca/Mg concentrations. Our findings are compatible with the view that the peripheral layer of the fundamental nuclear protein-framework, the so-called nuclear matrix, can modulate, inter alia, the lipid distribution and fluidity, respectively, in nuclear membranes. We suggest that a contraction of the nuclear matrix's peripheral layer induces a contraction of the nuclear membranes which, in turn, leads to an isothermic lateral lipid segregation within nuclear membranes. KEY WORDS nuclear envelope nuclear membranes nuclear matrix membrane lipid fluidity isothermic membrane lipid segregation Biomembranes are widely considered as being 'fluid' entities, i.e., membrane integral proteins can diffuse laterally and/or rotationally within a fluid lipid bilayer continuum (41). Recently, evidence has accumulated that the mobility of membrane integral proteins can be controlled, inter alia, by membrane-associated skeletal proteins (e.g., references 11, 37, 42, 53).J. CELL BIOLOGY ~ The Rockefeller University Press 9

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“…Therefore, the resemblance of the "high" range spectra obtained here (Fig. 3B and E) to the corresponding spectra of other membrane systems labelled with presumably low probe concentrations [7,8,11,17,25,26,34,36,43,44,52,58,59,62,65,66,70] suggests the possibility that radical interactions might have interfered with the measurement of intrinsic membrane properties in previous studies.…”

Section: Discussionmentioning

confidence: 61%

“…Calcium has also been reported to mediate decreases in the fluidity of several other 1(12, 3)-labelled membranes, including Bacillus subtilis cytoplasmic membranes [17] and the model membranes phosphatidylserine [54] and cardiolipin [25]. However, these findings must be regarded with caution since calcium has been shown to induce probe segregation in several model membranes I-6, 53, 54].…”

Section: Discussionmentioning

confidence: 94%

“…Probe-probe interactions were judged to be negligible in the unexpanded spectra of I(12,3)-labelled rat liver plasma membrane and phosphatidylserine before and after addition of calcium; moreover, the m ratio of liver plasma membrane was not changed by calcium binding at 31 and 37 ~ . Both the Bacillus subtilis [17] and cardiolipin [25] studies neglected the possibility of a divalent cation-mediated probe segregation in the bilayer. However, the unexpanded spectrum of I(12, 3)-labelled cardiolipin obtained after addition of CaC12 appears to exhibit characteristic exchange-broadened features.…”

Section: Discussionmentioning

confidence: 99%

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Spin-label studies on rat liver and heart plasma membranes: Do probe-probe interactions interfere with the measurement of membrane properties?

et al. 1977

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The structures of purified rat liver and heart plasma membranes were studied with the 5-nitroxide stearic acid spin probe, I(12,3). ESR spectra were recorded with a 50 gauss field sweep, and also with a new technique which "expands" the spectrum by (1) recording pairs of adjoining peaks with a smaller field sweep and (2) superposing the common peaks. The hyperfine splittings measured from the "expanded" spectra were significantly more precise than those obtained from the "unexpanded" spectra. Both procedures were used to study the effects of various I(12,3) probe concentrations on the spectra of liver and heart membranes, as well as the effects of temperature and CaCl2 additions on the spectra of liver membranes, and revealed the following: The polarity-corrected order parameters of liver (31 degrees) and heart (22 degrees) membranes were found to be independent of the probe concentration, if experimentally-determined low I(12,3)/lipid ratios were employed. The absence of obvious radical-interaction broadening in the unexpanded spectra indicated that "intrinsic" membrane properties may be measured at these low probe/lipid ratios. Here, "intrinsic" properties are defined as those which are measured when probe-probe interactions are negligible, and do not refer to membrane behavior in the absence of a perturbing spin label. At higher I(12,3)/lipid ratios, the order parameters of liver and heart membranes were found to substantially decrease with increasing probe concentration. The increase in the "apparent" fluidity of both membrane systems is attributed to enhanced radical interactions; however, an examination of these spectra (without reference to "low" probe concentration spectra) might incorrectly suggest that radical interactions were absent. For the membrane concentrations employed in these studies, the presence of "liquid-lines" (or "fluid components") in the unexpanded ESR spectra was a convenient marker of high probe concentrations. A thermotropic phase separation was observed in liver membranes between 19 degrees and 28 degrees. Addition of CaCl2 to liver plasma membrane [labelled with "low" I(12,3) concentrations] increased the rigidity of the membrane at 31 degrees and 37 degrees, without inducing a segregation of the probe in the bilayer. Previously reported data are discussed in relation to these results, and suggested minimal criteria for performing membrane spin label studies are included.

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The effect of calcium on temperature-induced phase changes in liquid-crystalline cardiolipin structure

Cited by 30 publications

References 19 publications

Distance estimate of the active center of D-.beta.-hydroxybutyrate dehydrogenase from the membrane surface

Distance estimate of the active center of D-.beta.-hydroxybutyrate dehydrogenase from the membrane surface

Expansion and apparent fluidity decrease of nuclear membranes induced by low Ca/Mg. Modulation of nuclear membrane lipid fluidity by the membrane-associated nuclear matrix proteins?

Spin-label studies on rat liver and heart plasma membranes: Do probe-probe interactions interfere with the measurement of membrane properties?

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