Biological membranes

The use of natural-origin active compounds in disease treatment is currently a prevailing trend. Mangiferin, a major component found in mangoes, is present in relatively high proportions. However, mangiferin's disadvantages include low solubility and poor permeability. There are numerous methods available to improve solubility and permeability, among which selfassembly is noteworthy.

10p vinara 11-01-2025 1 0   Download

Basic Cell Biology I. Cytoplasm A. Plasma membrane B. Mitochondria C. Ribosomes D. Endoplasmic reticulum 1. Rough 2. Smooth E. Golgi apparatus F. Lysosomes G. Cytoskeleton II. Nucleus A. Nuclear Envelope B. Chromatin C. Nucleolus D. Nuclear matrix III. Cell division .© 2002 by Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter. .Asymmetrical arrangement of phospholipids in plasma membrane ATP-dependent phospholipid translocase .Molecular Cell Biology, Lodish et al., 4th edition. .Figure 2—1.

68p whitedaisy1010 26-02-2013 63 12   Download

The research herein builds on the work of Rojek (2003) and further investigates the bioremediation of NOM wastes. The aim of this research was to evaluate the effectiveness of selected white-rot fungi and yeast for the biodegradative removal of concentrated NOM from solution. The effectiveness of the white-rot fungus P. chrysosporium ATCC 34541 for the biological degradation of different batches of MIEXTM NOM concentrate and the effects of different characteristics of the NOM on the process and thus the resistance of the NOM to microbial removal were investigated.

131p runthenight05 01-03-2023 10 3   Download

Department of Medical Biochemistry and Biology, University of Bari, Italy; 2Department of Zoology, Laboratory of Histology and Comparative Anatomy, University of Bari, Italy; 3Center for the Study of Mitochondria and Energy Metabolism (CNR) Bari, Italy Mitochondrial bioenergetic impairment has been found in the organelles isolated from rat liver during the prereplicative phase of liver regeneration.

9p system191 01-06-2013 35 4   Download

In a previous study, the S100A8/A9 protein, a Ca2+- and arachidonic acid-binding protein, abundant in neutrophil cytosol, was found to potentiate the activation of the redox component of the O2– generating oxidase in neutrophils, namely the membrane-bound flavocytochrome b, by the cytosolic phox proteins p67phox, p47phox and Rac ` (Doussiere J., Bouzidi F. and Vignais P.V. (2001) Biochem. Biophys. Res. Commun. 285, 1317–1320). This led us to check by immunoprecipitation and protein fractionation whether the cytosolic phox proteins could bind to S100A8/A9.

10p system191 01-06-2013 30 4   Download

Mikrobiologisches Institut der Eidgeno¨ssischen Technischen Hochschule, ETH-Zentrum, Zu¨rich, Switzerland The membrane-bound b subunit of the oxaloacetate decarboxylase Na+ pump of Klebsiella pneumoniae catalyzes the decarboxylation of enzyme-bound biotin. This event is coupled to the transport of 2 Na+ ions into the periplasm and consumes a periplasmically derived proton. The connecting fragment IIIa and transmembrane helices IV and VIII of the b subunit are highly conserved, harboring residues D203, Y229, N373, G377, S382, and R389 that play a profound role in catalysis. ...

8p system191 01-06-2013 33 4   Download

P-glycoprotein (Pgp), a membrane pump often responsible for the multidrug resistance of cancer cells, undergoes conformational changes in the presence of substrates/modulators, or upon ATP depletion, reflected by its enhanced reactivity with the UIC2 monoclonal antibody. When the UIC2-shift was elicited by certain modulators (e.g. cyclosporin A or vinblastine, but not with verapamil or Tween 80), the subsequent binding of other monoclonal anti-Pgp Ig sharing epitopes with UIC2 (e.g. MM12.10) was abolished [Nagy, H., Goda, K., Arceci, R., Cianfriglia, M., ´ Mechetner, E. & Szabo Jr, G.

6p system191 01-06-2013 62 7   Download

School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK; 2Shifa College of Medicine, Islamabad, Pakistan.Curcumin is a compound derived from the spice, tumeric. It is a potent inhibitor of the SERCA Ca2þ pumps (all isoforms), inhibiting Ca2þ-dependent ATPase activity with IC50 values of between 7 and 15 mM . It also inhibits ATPdependent Ca2þ-uptake in a variety of microsomal membranes, although for cerebellar and platelet microsomes, a stimulation in Ca2þ uptake is observed at low curcumin concentrations (,10 mM )....

10p system191 01-06-2013 37 5   Download

Intracellular pH homeostasis in the filamentous fungus Aspergillus niger was measured in real time by 31P NMR during perfusion in the NMR tube of fungal biomass immobilized in Ca2+-alginate beads. The fungus maintained constant cytoplasmic pH (pHcyt) and vacuolar pH (pHvac) values of 7.6 and 6.2, respectively, when the extracellular pH (pHex) was varied between 1.5 and 7.0 in the presence of citrate. Intracellular metabolism did not collapse until a DpH over the cytoplasmic membrane of 6.6–6.7 was reached (pHex 0.7–0.8).

10p research12 01-06-2013 42 4   Download

The amyloid protein precursor (APP) was incorporated into liposomes or phospholipid monolayers. APP insertion into liposomes required neutral lipids, such as L-a-phosphatidylcholine, in the target membrane. It was prevented in vesicles containing L-a-phosphatidylserine. The insertion was enhanced in acidic solutions, suggesting that it is modulated by specific charge/charge interactions. Surfaceactive properties and behaviour of APP were characterized during insertion of the protein in monomolecular films of L-a-phosphatidylcholine, L-a-phosphatidylethanolamine or L-a-phosphatidylserine. ...

9p research12 01-06-2013 42 4   Download

The activity of outer membrane phospholipase A (OMPLA) is regulated by reversible dimerization. However, native OMPLA reconstituted in phospholipid vesicles was found to be present as a dimer but nevertheless inactive. To investigate the importance of dimerization for control of OMPLA activity, a covalent OMPLA dimer was constructed and its properties were compared to native OMPLA both in a micellar detergent and after reconstitution in a phospholipid bilayer.

8p research12 01-06-2013 34 4   Download

A severe challenge to the idea that mitochondrial DNA mutations play a major role in the aging process in mammals is that clear loss-of-function mutations accumulate only to very low levels (under 1% of total) in almost any tissue, even by very old age. Their accumulation is punctate: some cells become nearly devoid of wild-type mitochondrial DNA and exhibit no activity for the partly mitochondrially encoded enzyme cytochrome c oxidase. Such cells accumulate in number with aging, suggesting that they survive indefinitely, which is itself paradoxical....

7p research12 01-06-2013 27 3   Download

Subunits (a, b and c) of the interleukin-2 receptor complex (IL-2R) are involved in both proliferative and activationinduced cell death (AICD) signaling of T cells. In addition, the signaling b and c chains are shared by other cytokines (e.g. IL-7, IL-9, IL-15). However, the molecular mechanisms responsible for recruiting/sorting the a chains to the signaling chains at the cell surface are not clear.

10p research12 01-06-2013 30 5   Download

Na + /K + -ATPase as an energy transducing ion pump has beenstudiedextensivelysince itsdiscovery in1957.Although early findings suggested a role for Na + /K + -ATPase in regulation of cell growth and expression of various genes, only in recent years the mechanisms through which this plasma membrane enzyme communicates with the nucleus have been studied.

6p research12 29-04-2013 34 4   Download

Tyrosine hydroxylase (TH) demonstrates by two-dimen-sional electrophoresis amicroheterogeneitybothas a soluble recombinant humanTH(hTH1) andas amembrane-bound bovine TH (bTHmem). Part of the heterogeneity is likely due to deamidation of labile asparagine residues. Wild-type (wt)-hTH1was foundtobeasubstrate for theubiquitin(Ub) conjugating enzyme systemina reconstitutedin vitrosystem.

9p research12 29-04-2013 61 4   Download

In order to study the pressure-induced changes of biological membrane, hydrostatic pressures of from 0.1 to 400 MPa were applied to membrane-bound Na + /K + -ATPase from pigkidneyas amodel systemof proteinand lipidmembrane. The activity showed at least a three-step change induced by pressures of 0.1±100 MPa, 100±220 MPa, and 220 MPa or higher.

9p research12 29-04-2013 25 2   Download

Melanotransferrin (MTf) is a membrane-bound transferrin (Tf) homologue foundparticularly inmelanoma cells. Apart frommembrane-boundMTf, a soluble formof themolecule (sMTf) has been identified in vitro [Food, M.R., Rothen-berger, S., Gabathuler, R., Haidl, I.D., Reid, G. & Jefferies, W.A. (1994)J. Biol. Chem.269, 3034–3040] and in vivo in Alzheimer’s disease. However, nothing is known about the functionof sMTf or its role inFeuptake.

11p research12 23-04-2013 21 1   Download

OprM, the outer membrane component of the MexAB-OprM multidrug efflux pump ofPseudomonas aeruginosa, hasbeenassumed to facilitate the export of antibiotics across the outer membrane of this organism. Here we purified to homogeneity the OprM protein, reconstituted it into lipo-somemembranes, and tested its channel activitybyusing the liposome swellingassay. Itwas demonstrated thatOprMis a channel-forming protein and exhibits the channel property that amino acids diffuse more efficiently than saccharides....

8p research12 23-04-2013 40 4   Download

ThemaltoseATP-binding cassette transporter ofSalmonella typhimurium is composed of a membrane-associated com-plex (MalFGK2) and a periplasmic receptor (MalE). In addition to its role in transport, the complex acts as a repressor ofmaltose-regulatedgene expressionand is subject to inhibition in the process of inducer exclusion. These activities are thought to be mediated by interactions of the ATPase subunit, MalK, with the transcriptional activator, MalT, and nonphosphorylated enzyme IIA of the glucose phosphotransferase system, respectively. ...

12p research12 23-04-2013 35 3   Download

The interactionofmany lytic cationic antimicrobial peptides with their target cells involves electrostatic interactions, hydrophobic effects, and the formation of amphipathic sec-ondary structures, such asahelices orbsheets. We have shown in previous studies that incorporating
30% D-aminoacids intoashortahelical lyticpeptidecomposedof leucine and lysine preserved the antimicrobial activity of the parent peptide, while the hemolytic activity was abolished.

12p research12 23-04-2013 35 2   Download