Fluorescence properties of Langmuir-Blodgett films of chlorophyll a mixed with membrane lipids

Picard, G.; Aghion, Jacques; Crom, C. Le; Leblanc, Roger M.

doi:10.1016/0040-6090(89)90051-5

Cited by 22 publications

(9 citation statements)

References 32 publications

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“…It may be added that the corresponding excitation spectrum exhibits bands at 438 nm and 673 nm. All of these characteristics are comparable to those of a mixed film of chlorophyll a and monogalactosyldiacylglycerol in a molar ratio of 1 : 100 (chlorophyll a/monogalactosyldiacylglycerol) [31]. It can therefore be argued that in mixed chlorophyll-protein films, chlorophyll a is diluted by cytochrome c, as it is in mixed films by monogalactosyldiacylglycerol.…”

Section: Resultssupporting

confidence: 54%

“…This is in contrast with the appearance of an important slow component (z 4.5 ns; SO%), attribuable to the dilution of chlorophyll a with monogalactosyldiacylglycerol(1: 100) [31]. Therefore, the mixed chlorophyll a-cytochrome c complex behaves like a diluted chlorophyll a mixture, in regard to its absorption and fluorescence spectra, while its measured fluorescence-lifetime, shorter or equal to 0.2 ns, has the characteristics of a concentrated chlorophyll a system.…”

Section: Resultsmentioning

confidence: 53%

See 1 more Smart Citation

Complex formation between chlorophyll a and cytochrome c: surface properties at the air‐water interface

Lamarche¹,

Picard

Téchy

et al. 1991

European Journal of Biochemistry

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The binding of cytochrome c to an insoluble monolayer of chlorophyll a was studied. Surface pressure (n), surface potential ( A V) and ['4C]cytochrome c surface-concentration (r) isotherms were measured versus molecular area (a) in mixed films. Compared to the successive-addition method, this procedure allows the formation of homogeneous mixed films. The cytochrome c is incorporated into a chlorophyll a monolayer, compressed at a surface pressure of 20 mN . m-'. On expansion, the quantity of protein incorporated into the monolayer gradually increases. Subsequent compression-expansion cycles result in similar isotherms, distinct from that measured during the first expansion. All surface properties measured, but more specifically the surface radioactivity of ['4C]cytochrome c, indicate the irreversibility of protein incorporation into the chlorophyll a monolayer. In fact, surface properties of the binary film are completely different from the properties of either of the pure components. As a result, calculated values of surface potentials for mixed films using the additivity law deviate from experimentally measured potentials. The absorption and fluorescence spectra of mixed films transferred onto a solid substrate by the Langmuir-Blodgett technique, indicate a dilution effect of chlorophyll a by cytochrome c. However, the dilution effect cannot be detected by the fluorescence lifetimes of pure chlorophyll a and mixed chlorophyll a-cytochrome c films, both shorter than 0.2 ns. This provides support for the existence of an energytransfer mechanism between chlorophyll a monomer and chlorophyll a aggregates which could serve as an energy trap. The role of the protein could be related to that of the matrix.The morphological basis of biological functions in membranes is very difficult to determine, due to the complexity, with regard to both the organization and nature of membrane components. In photosynthetic membranes it is known that chlorophyll is associated with membrane proteins [l -31. Such molecular associations can only be extracted and purified with the use of detergents, which can be reasonably assumed to affect their integrity. Therefore, synthetic approaches have been considered in order to reconstitute, gradually, the biological membrane functions. The monolayer technique is widely used, since it allows a fine control of molecular orientation and it deals with concentrations similar to those found in natural membranes. Furthermore, this technique permits the study of the effects of different parameters, such as temperature, pH and ionic strength, either in succession or simultaneously. Finally, monolayer methods can be used to investigate mixed films with pure components, alone or mixed in any molar ratio. Despite such advantages, it is not easy to investigate chlorophyll-protein complexes using monolayer methods, since the integral proteins are highly hydrophobic Correspondence to R. M. Leblanc, Centre de recherche en photobiophysique, Universite du Quebec a Trois-Rivieres, C.P. 500, TroisRivikres, Quebec...

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Section: Resultssupporting

confidence: 54%

Section: Resultsmentioning

confidence: 53%

Complex formation between chlorophyll a and cytochrome c: surface properties at the air‐water interface

Lamarche¹,

Picard

Téchy

et al. 1991

European Journal of Biochemistry

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“…This component can be attributed to Chl a released from PPC because its lifetime is very close to the lifetime range of free Chl a in solution (;5.5-6.5 ns) (55). Moreover, this 5 ns component noticeably resembles the decay component of the monomeric Chl a form in membrane lipids (56). This attribution is further supported by the findings that 1) the Chl a fluorescence maximum of this leaf in the M2 FTC region (i.e.…”

Section: Origin Of Fluorescence Rise At 55-608cmentioning

confidence: 76%

Origin of Chlorophyll Fluorescence in Plants at 55–75°C¶

Ilı́k

Kouřil

Kruk³

et al. 2003

Photochem Photobiol

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The origin of heat-induced chlorophyll fluorescence rise that appears at about 55-60 degrees C during linear heating of leaves, chloroplasts or thylakoids (especially with a reduced content of grana thylakoids) was studied. This fluorescence rise was earlier attributed to photosystem I (PSI) emission. Our data show that the fluorescence rise originates from chlorophyll a (Chl a) molecules released from chlorophyll-containing protein complexes denaturing at 55-60 degrees C. This conclusion results mainly from Chl a fluorescence lifetime measurements with barley leaves of different Chl a content and absorption and emission spectra measurements with barley leaves preheated to selected temperatures. These data, supported by measurements of liposomes with different Chl a/lipid ratios, suggest that the released Chl a is dissolved in lipids of thylakoid membranes and that with increasing Chl a content in the lipid phase, the released Chl a tends to form low-fluorescing aggregates. This is probably the reason for the suppressed fluorescence rise at 55-60 degrees C and the decreasing fluorescence course at 60-75 degrees C, which are observable during linear heating of plant material with a high Chl a/lipid ratio (e.g. green leaves, grana thylakoids, isolated PSII particles).

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“…This component can be attributed to Chl a released from PPC because its lifetime is very close to the lifetime range of free Chl a in solution (∼5.5–6.5 ns) (55). Moreover, this 5 ns component noticeably resembles the decay component of the monomeric Chl a form in membrane lipids (56). This attribution is further supported by the findings that 1) the Chl a fluorescence maximum of this leaf in the M2 FTC region ( i.e.…”

Section: Discussionmentioning

confidence: 87%

Origin of Chlorophyll Fluorescence in Plants at 55-75°C¶

Ilı́k

Kouřil

Kruk

et al. 2007

Photochemistry and Photobiology

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The origin of heat‐induced chlorophyll fluorescence rise that appears at about 55–60°C during linear heating of leaves, chloroplasts or thylakoids (especially with a reduced content of grana thylakoids) was studied. This fluorescence rise was earlier attributed to photosystem I (PSI) emission. Our data show that the fluorescence rise originates from chlorophyll a (Chl a) molecules released from chlorophyll‐containing protein complexes denaturing at 55–60°C. This conclusion results mainly from Chl a fluorescence lifetime measurements with barley leaves of different Chl a content and absorption and emission spectra measurements with barley leaves preheated to selected temperatures. These data, supported by measurements of liposomes with different Chl a/lipid ratios, suggest that the released Chl a is dissolved in lipids of thylakoid membranes and that with increasing Chl a content in the lipid phase, the released Chl a tends to form low‐fluorescing aggregates. This is probably the reason for the suppressed fluorescence rise at 55–60°C and the decreasing fluorescence course at 60–75°C, which are observable during linear heating of plant material with a high Chl a/lipid ratio (e.g. green leaves, grana thylakoids, isolated PSII particles).

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Fluorescence properties of Langmuir-Blodgett films of chlorophyll a mixed with membrane lipids

Cited by 22 publications

References 32 publications

Complex formation between chlorophyll a and cytochrome c: surface properties at the air‐water interface

Complex formation between chlorophyll a and cytochrome c: surface properties at the air‐water interface

Origin of Chlorophyll Fluorescence in Plants at 55–75°C¶

Origin of Chlorophyll Fluorescence in Plants at 55-75°C¶

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