The Effect of Cholesterol on the Solution Structure of Proteins of Photosystem II. Protein Secondary Structure and Photosynthetic Oxygen Evolution

Bograh, A.; Carpentier, Robert; Tajmir-Riahi, H.A.

doi:10.1006/jcis.1998.5949

Cited by 6 publications

(3 citation statements)

References 24 publications

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“…In addition, amide I of bLf entrapped in liposomes had no shift in peak position compared with free bLf. Interestingly, amide II band at 1514.65 per cm disappeared or overlapped after entrapment in liposomes, which was attributed to cholesterol interaction with the polypeptide and phospholipid polar groups , allowed the insertion of bLf into the bilayer forming discoidal phospholipid–peptide assemblies . With respect to SLP, the absence of any shift in protein peak positions after encapsulation exhibited that there was no detectable structural change in bLf associated with the compositions of SLPs.…”

Section: Discussionmentioning

confidence: 99%

Preparation, Optimization and Characterization of Bovine Lactoferrin‐loaded Liposomes and Solid Lipid Particles Modified by Hydrophilic Polymers Using Factorial Design

et al. 2014

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Bioadhesive liposomes and solid lipid particles (SLPs) modified by pectin and chitosan for oral administration of bovine lactoferrin (bLf) were prepared using a 2(4) full-factorial design to identify the key formulation variables influencing particle size and drug entrapment efficiency (EE). Netlike structures of the polymer-particle mixture consisting of a polymeric network in which multiple particles were imbedded were observed by scanning electron microscopy (SEM). Chemical stability of bLf after encapsulation into pectin- and chitosan-modified liposomes and SLPs was confirmed by Fourier transform infrared spectra (FTIR). Bovine lactoferrin was located within phospholipid bilayer, whereas in SLPs bLf was within the matrix. The crystalline nature of bLf after encapsulation was investigated by differential scanning calorimetry (DSC) of drug-loaded particles, indicating amorphous dispersion of bLf in the polymer-lipid matrix of pectin- and chitosan-modified liposomes and SLPs. In vivo pharmacokinetic investigation of bLf in pectin- and chitosan-modified liposomes and SLPs showed prolonged mean residence time (MRT) of bLf in rat blood and increased the relative bioavailability (Fbio %) by 1.95- to 2.69-fold compared with free bLf. The developed carrier systems are considered to be promising vehicles for oral delivery.

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Section: Discussionmentioning

confidence: 99%

Preparation, Optimization and Characterization of Bovine Lactoferrin‐loaded Liposomes and Solid Lipid Particles Modified by Hydrophilic Polymers Using Factorial Design

et al. 2014

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“…nAChr is reportedly shown to be stabilized in its activated form by a direct action of cholesterol [19]. There are spectroscopic analyses showing that variation in cholesterol concentration can perturb protein secondary structure; this has been shown in photosystem II [67].…”

Section: Discussionmentioning

confidence: 99%

Restoration of IFNγR Subunit Assembly, IFNγ Signaling and Parasite Clearance in Leishmania donovani Infected Macrophages: Role of Membrane Cholesterol

et al. 2011

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Despite the presence of significant levels of systemic Interferon gamma (IFNγ), the host protective cytokine, Kala-azar patients display high parasite load with downregulated IFNγ signaling in Leishmania donovani (LD) infected macrophages (LD-MØs); the cause of such aberrant phenomenon is unknown. Here we reveal for the first time the mechanistic basis of impaired IFNγ signaling in parasitized murine macrophages. Our study clearly shows that in LD-MØs IFNγ receptor (IFNγR) expression and their ligand-affinity remained unaltered. The intracellular parasites did not pose any generalized defect in LD-MØs as IL-10 mediated signal transducer and activator of transcription 3 (STAT3) phosphorylation remained unaltered with respect to normal. Previously, we showed that LD-MØs are more fluid than normal MØs due to quenching of membrane cholesterol. The decreased rigidity in LD-MØs was not due to parasite derived lipophosphoglycan (LPG) because purified LPG failed to alter fluidity in normal MØs. IFNγR subunit 1 (IFNγR1) and subunit 2 (IFNγR2) colocalize in raft upon IFNγ stimulation of normal MØs, but this was absent in LD-MØs. Oddly enough, such association of IFNγR1 and IFNγR2 could be restored upon liposomal delivery of cholesterol as evident from the fluorescence resonance energy transfer (FRET) experiment and co-immunoprecipitation studies. Furthermore, liposomal cholesterol treatment together with IFNγ allowed reassociation of signaling assembly (phospho-JAK1, JAK2 and STAT1) in LD-MØs, appropriate signaling, and subsequent parasite killing. This effect was cholesterol specific because cholesterol analogue 4-cholestene-3-one failed to restore the response. The presence of cholesterol binding motifs [(L/V)-X1–5-Y-X1–5-(R/K)] in the transmembrane domain of IFNγR1 was also noted. The interaction of peptides representing this motif of IFNγR1 was studied with cholesterol-liposome and analogue-liposome with difference of two orders of magnitude in respective affinity (KD: 4.27×10−9 M versus 2.69×10−7 M). These observations reinforce the importance of cholesterol in the regulation of function of IFNγR1 proteins. This study clearly demonstrates that during its intracellular life-cycle LD perturbs IFNγR1 and IFNγR2 assembly and subsequent ligand driven signaling by quenching MØ membrane cholesterol.

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“…An alternative possibility is that because of its ability to fold and unfold KMP-11 may interact with the membrane lipid (18). There is spectroscopic evidence showing that variation in the cholesterol concentration in the membrane can perturb the protein secondary structure; this has been well studied in photosystem II of chloroplasm (8) and in the cholecystokinin receptor (24).…”

Section: Discussionmentioning

confidence: 99%

Designing Therapies against Experimental Visceral Leishmaniasis by Modulating the Membrane Fluidity of Antigen-Presenting Cells

et al. 2009

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The membrane fluidity of antigen-presenting cells (APCs) has a significant bearing on T-cell-stimulating ability and is dependent on the cholesterol content of the membrane. The relationship, if any, between membrane fluidity and defective cell-mediated immunity in visceral leishmaniasis has been investigated. Systemic administration of cholesterol by liposome delivery (cholesterol liposomes) in Leishmania donovaniinfected hamsters was found to cure the infection. Splenic macrophages as a prototype of APCs in infected hamsters had decreased membrane cholesterol and an inability to drive T cells, which was corrected by cholesterol liposome treatment. The effect was cholesterol specific because liposomes made up of the analogue 4-cholesten-3-one provided almost no protection. Infection led to increases in interleukin-10 (IL-10), transforming growth factor beta, and IL-4 signals and concomitant decreases in gamma interferon (IFN-␥), tumor necrosis factor alpha, and inducible NO synthase signals, which reverted upon cholesterol liposome treatment. The antileishmanial T-cell repertoire, whose expansion appeared to be associated with protection, was presumably type Th1, as shown by enhanced IFN-␥ signals and the predominance of the immunoglobulin G2 isotype. The protected group produced significantly more reactive oxygen species and NO than the infected groups, which culminated in killing of L. donovani parasites. Therefore, cholesterol liposome treatment may be yet another simple strategy to enhance the cell-mediated immune response to L. donovani infection. To our knowledge, this is the first report on the therapeutic effect of cholesterol liposomes in any form of the disease.

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The Effect of Cholesterol on the Solution Structure of Proteins of Photosystem II. Protein Secondary Structure and Photosynthetic Oxygen Evolution

Cited by 6 publications

References 24 publications

Preparation, Optimization and Characterization of Bovine Lactoferrin‐loaded Liposomes and Solid Lipid Particles Modified by Hydrophilic Polymers Using Factorial Design

Preparation, Optimization and Characterization of Bovine Lactoferrin‐loaded Liposomes and Solid Lipid Particles Modified by Hydrophilic Polymers Using Factorial Design

Restoration of IFNγR Subunit Assembly, IFNγ Signaling and Parasite Clearance in Leishmania donovani Infected Macrophages: Role of Membrane Cholesterol

Designing Therapies against Experimental Visceral Leishmaniasis by Modulating the Membrane Fluidity of Antigen-Presenting Cells

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