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PubMed2006

Synthesis of Pseudomonas quorum-sensing autoinducer analogs and structural entities required for induction of apoptosis in macrophages.

The synthesis of the analogs of N-3-oxododecanoyl-L-homoserine lactone (1) and their structure-activity relationship for the apoptotic induction in macrophages, P388D1 cells, are described. It was revealed that the position of the oxo group in the acyl side chain in addition to the presence of the L-homoserine lactone unit is crucial for the apoptosis-inducing activity. Furthermore, the long acyl side chains with hydrophobic distal ends are preferable for the activity.

4-Butyrolactone↗

PubMed1999

Mitochondrial fatty acid oxidation disorders and cyclic vomiting syndrome.

Inherited fatty acid oxidation (FAO) disorders represent a relatively new group of inborn errors of metabolism. Although our understanding of the biochemical and molecular bases of these disorders has improved dramatically in recent years, many patients remain undetected or are given other diagnoses, cyclic vomiting syndrome (CVS) being one of them in a few known cases. Medium chain acyl-CoA dehydrogenase deficiency and the late-onset form of glutaric acidemia type II have been anecdotally misdiagnosed as CVS. In addition, short chain acyl-CoA dehydrogenase deficiency (either true defects or polymorphism-related phenotypes) and particularly short-chain 3-hydroxy acyl-CoA dehydrogenase deficiency may present with clinical and biochemical features that closely resemble CVS. However, the collective role played by FAO and probably other metabolic disorders among the causes of CVS in unknown. Guidelines for a diagnostic approach to FAO disorders at the biochemical level are being presented and discussed. Hopefully, a better understanding and an awareness of FAO disorders could improve the diagnostic evaluation of patients with CVS.

Acyl-CoA Dehydrogenases↗

PubMed2005

Topography of diphtheria toxin A chain inserted into lipid vesicles.

The membrane-inserting T domain of diphtheria toxin aids the low-pH-triggered translocation of the catalytic A chain of the toxin across endosomal membranes. To evaluate the role of the isolated A chain in translocation, the topography of isolated A chain inserted into model membrane vesicles was investigated using a mixture either of dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylglycerol (DOPG) or of dimyristoleoylphosphatidylcholine (DMoPC) and DOPG. The latter mixture was previously found to promote deep insertion of the T domain. A series of single Cys mutants along the A chain sequence were labeled with bimane or BODIPY groups. After A chain insertion into model membranes, the location of these groups within the lipid bilayer was determined via bimane fluorescence emission lambda(max), binding of externally added anti-BODIPY antibodies, and a novel technique involving the comparison of the quenching of bimane fluorescence by aqueous iodide and membrane-associated 10-doxylnonadecane. The results show that in both DOPC- and DMoPC-containing bilayers, membrane-inserted residues all along the A chain sequence occupy shallow locations that are relatively exposed to the external solution. There were only small differences between A chain topography in the two different types of lipid mixtures. However, the behavior of the A chain in the two different lipid mixtures was distinct in that it strongly oligomerized in DMoPC-containing vesicles as judged by Trp fluorescence. In addition, A chain selectively induced fusion of the DMoPC-containing vesicles, and this may aid oligomerization by increasing the A chain/vesicle ratio. Fusion may also explain why A chain also selectively induced leakage of the contents of DMoPC-containing vesicles. We propose that isolated A chain is unlikely to be inserted in a transmembrane orientation, and thus its interaction with the T domain is likely to be critical for properly orienting the A chain within the bilayer in a fashion that allows translocation.

4-Chloro-7-nitrobenzofurazan↗

PubMed1996

Type VIII collagen is a product of vascular smooth-muscle cells in development and disease.

Type VIII collagen is a short-chain collagen with considerable similarity to type X collagen. We have generated chain-specific antibodies to the alpha 1 and alpha 2 chains of type VIII collagen, and used them as probes to examine the synthesis of type VIII collagen by vascular smooth muscle cells (VSMC). In addition, chain-specific oligonucleotides have been used in reverse transcriptase-PCR (RT-PCR) reactions with RNA extracted from cultured smooth muscle cells in culture and from freshly isolated vascular tissues. Radiolabelling of VSMC in culture and immunoprecipitation with chain-specific antibodies showed that both chains were expressed. Lower levels of type VIII collagen were found in adult VSMC than in neonatal VSMC. RT-PCR showed that both chains were expressed in tissues as well as cells in culture. The results indicate that type VIII collagen is a product of VSMC of normal adult vessels and is expressed at high levels by VSMC in vascular lesions.

Adult↗

PubMed1980

The asparagine-linked sugar chains of the glycoproteins in calf thymocyte plasma membrane. Structural studies of acidic oligosaccharides.

The acidic oligosaccharide fraction obtained by paper electrophoresis of the hydrazinolysate of the plasma membrane glycoprotein mixture of calf thymocytes was fractionated by high voltage paper electrophoresis into 15 acidic components. Three of them were mixtures of two acidic oligosaccharides, while the remaining 12 were almost pure acidic oligosaccharides. The 18 oligosaccharides have a common core hexasaccharide, Man alpha 1 yields 6(man beta 1 yields 3)Man beta 1 yields 4GlcNAc beta 1 yields 4(Fuc alpha 1 yields 6)GlcNAc. The number of outer chains ranges from two to four. Three different types of outer chains, Gal beta 1 yields 4 GlcNAc beta 1 yields, Gal beta 1 yields 3 GlcNAc beta 1 yields, and Gal beta 1 yields 4 GlcNAc beta 1 yields 3Gal beta 1 yields 4GlcNAc beta 1 yields, were found to occur in the acidic oligosaccharides in various combination. In the biantennary oligosaccharides, the two outer chains are linked only at the C-2 position of the two alpha-mannosyl residues of the core hexasaccharide. All triantennary oligosaccharides have an additional outer chain at the C-4 position of the alpha-mannosyl residue constructing the Man alpha 1 yields 6Man group of the core. Two outer chains of tetraantennary oligosaccharides are linked at the C-2 and 4 positions of one alpha-mannosyl residue and the remaining two outer chains at the C-2 and 6 positions of the other alpha-mannosyl residue of the core. An interesting observation is that C-2,6 disubstitution always occurs on the alpha-mannosyl residue of the Man alpha 1 yields 6 side in all oligosaccharides with Gal beta 1 yields 4GlcNAc beta 1 yields 3Gal beta 1 yields 4GlcNAc beta 1 yields outer chain, while in other tetraantennary oligosaccharides, C-2,6 disubstitution always occurs on the alpha-mannosyl residue of the Man alpha 1 yields 3 side. No sialylated Gal beta 1 yields 3Gal beta 1 yields 4GlcNAc beta 1 yields outer chain was found in the acidic oligosaccharides studied in this paper.

Animals↗

PubMed1996

O-glycosylation of fibrinogen from different mammalian species as revealed by the binding of Escherichia coli biotinylated lectins.

After the demonstration that neither N-glycans nor neuraminic acid are involved in the binding of K88 lectins to the B beta and gamma chains of porcine fibrinogen and that their recognition was due to O-glycans (L'Hôte C, Berger S, Bourgerie S, Duval-Ifiah Y, Julien R, Karamanos Y. Infect Immun 1995; 63: 1927-1932) it clearly appeared that these lectins could be used as probes to detect O-glycans on fibrinogens of other species. The conclusion of the present study is that many mammalian fibrinogens contain complex O-glycans on B beta and gamma chains. In addition, the combined use of the biotinylated K99 lectin and the Peanut agglutinin demonstrated the presence of sialylated T-antigens on the A alpha chains of all the fibrinogens examined. These lectins can now be used to determine differences on the glycosylation status of fibrinogens within one species and also to detect O-glycans on other glycoproteins.

Animals↗

PubMed2001

Impaired immunoglobulin M production by incubation of hybridoma cells with ethanol.

Several reports have presented results that demonstrate suppression of the immune system by ethanol. Using a hybridoma cell model, we studied the effects of ethanol on cell proliferation and on the production of immunoglobulin M (IgM) antibodies. The number of cells decreased while incubated with as little as 25 mM ethanol but not in a clonal subline incapable of IgM production, indicative of an increased vulnerability associated with the antibody-producing machinery. Levels of antibodies in cell culture supernatants were monitored by -heavy-chain-specific and -light-chain-specific enzyme-linked immunosorbent assays. We found a significant decrease in antibody concentration at 200 mM ethanol compared with findings for nonexposed cells. In addition, lower -chain compared with -chain values were monitored at ethanol concentrations of 50 mM and higher. This difference suggests irregular composition of the antibodies in the supernatant. Determination of IgM levels within the hybridoma cells revealed a linear increase in antibody concentrations by as much as three times the control levels with increasing ethanol concentrations when correlated with cell numbers. Analysis of the mRNA levels of two ethanol-inducible stress proteins, the 78-kilodalton glucose-regulated protein (GRP78) and the 70-kilodalton heat-shock protein (HSC70), by quantitative Northern hybridization yielded increased mRNA in a nonlinear fashion. The results demonstrate that ethanol impairs IgM composition, whereas antibody production within hybridoma cells is increased and the assembling machinery is activated, indicating compensating processes.

Animals↗

PubMed1979

Amino acid sequence studies on the alpha chain of human fibrinogen. Overlapping sequences providing the complete sequence.

The complete amino acid sequence of the alpha chain of human fibrinogen has been determined. It contains 610 amino acid residues and has a calculated molecular weight of 66,124. The chain has 10 methionines, and fragmentation with cyanogen bromide yields 11 peptides [Doolittle, R.F., Cassman, K.G., Cottrell, B.A., Friezner, S.J., Hucko, J.T., & Takagi, T. (1977) Biochemistry 16, 1703]. The arrangement of the 11 fragments was determined by the isolation of peptide overlaps from plasmic and staphylococcal protease digests of fibrinogen and/or alpha chains. In addition, certain of the cyanogen bromide fragments, preliminary reports of whose sequences have appeared previously, have been reexamined in order to resolve several discrepancies. The alpha chain is homologous with the beta and gamma chains of fibrinogen, although a large repetitive segment of unusual composition is absent from the latter two chains. The existence of this unusual segment divides the sequence of the alpha chain into three zones of about 200 residues each that are readily distinguishable on the basis of amino acid composition alone.

Amino Acid Sequence↗

PubMed2005

The antibiotic and DNA-transfecting peptide LAH4 selectively associates with, and disorders, anionic lipids in mixed membranes.

The histidine-rich amphipathic peptide LAH4 has antibiotic and DNA delivery capabilities. The peptide has a strong affinity for anionic lipids found in the outer membrane of bacterial membranes. A role for anionic lipids in release of cationic plasmid-containing complexes has been proposed previously, and disruption of membrane asymmetry and presentation of phosphatidylserine (PS) in the membrane outer leaflet is a general feature observed in diseased mammalian cells. Therefore, to understand the peptide-lipid interactions in more detail, solid-state NMR experiments on model membranes have been performed. 31P MAS NMR on mixed phosphatidylcholine (PC)/PS and PC/phosphatidylglycerol (PG) membranes has been used to demonstrate a strong interaction between LAH4 and anionic lipids. By using deuterated lipids and wide-line 2H NMR when probing lipid chain order, it is demonstrated that LAH4 preferentially interacts with PS over PC and effectively disorders the anionic PS lipid fatty acyl chains. In addition, we demonstrate that the efficiency of gene transfer in vitro to different cell lines is closely related to the degree of disruption of PS acyl chains for four isomers of LAH4. This work suggests a mechanism of selective destabilization by LAH4 of anionic lipids in the membranes of cells during transfection with implications for nucleic acid delivery in vivo.

Amino Acid Sequence↗

PubMed2001

A simple calculation for the buildup and decay of radon progeny.

A Markov chain in conjunction with an electronic spreadsheet is used to generate the buildup and decay patterns of radon progeny in a procedure involving only multiplication and addition. Markov chains are highly suitable for calculations of this type. Because the Markov matrix may not be readily available, and because some health physicists may not be familiar with this procedure, we give the values of a Markov matrix and demonstrate how it can be used to produce a Markov chain describing the buildup and decay of radon progeny.

Markov Chains↗

PubMed1988

The B cell-associated CD37 antigen (gp40-52). Structure and subcellular expression of an extensively glycosylated glycoprotein.

The human B lymphocyte-associated CD37 antigen (gp40-52) has been characterized by the monoclonal antibody HD28. The CD37 antigen is strongly expressed on surface immunoglobulin positive B lymphocytes and weakly on a subpopulation of T lymphocytes and myeloid cells. The total molecular mass of the antigen ranges from approximately 40 to 52 kDa in B cell-derived leukemias and malignant lymphomas as well as in normal and anti-mu/B cell growth factor-activated tonsillar B cells. The polydisperse nature of the electrophoretic pattern of the CD37 antigen was found to be due to a microheterogeneity in its carbohydrate moiety. Biochemical analysis showed that the CD37 antigen derived from B cell-lines BJAB and LICR-LON-HMy2 consists of a single chain protein core of approximately 25 kDa to which two N-linked, complex carbohydrate antennae of various length are bound. The glycosylation of the molecule comprises about 50% of the total molecular mass. The molecule does not contain O-linked carbohydrate chains. In contrast, the non-Hodgkin's lymphoma cell line, OCI.LY1, which is growth-dependent on human serum, carries a CD37 antigen with an additional carbohydrate chain resulting in a total molecular mass of approximately 40 to 64 kDa. At the electron microscopy level, this cell surface-expressed antigen was found to be associated with intracellular vesicles. The subcellular distribution of the CD37 antigen may reflect a function of this antigen both at the cell surface and in the cytoplasm. We found that, both due to its peculiar biochemical structure and its ultrastructural distribution, the CD37 antigen closely resembles the 46-kDa species of the mannose 6-phosphate receptor. The implications of this possible congruence for the function of the CD37 antigen are discussed.

Animals↗

PubMed1985

Amino-terminal processing of proteins: hemoglobin South Florida, a variant with retention of initiator methionine and N alpha-acetylation.

The hemoglobin variant South Florida has been shown by protein sequencing and fast-atom-bombardment mass spectroscopy to have a substitution of methionine for the NH2-terminal valine of the beta-globin chain. In addition, there was complete retention of the initiator methionine on the mutant polypeptide. Approximately 20% of the protein was acetylated at the NH2 terminus of the beta chain. A search of a comprehensive data bank of protein and gene sequences revealed 84 unrelated vertebrate proteins that have not undergone cleavage of leader sequences. A highly nonrandom distribution of residues at the NH2 termini of these proteins predicts removal of the initiator methionine as well as NH2-terminal acetylation. Proteins that undergo removal commonly have serine, alanine, glycine, or valine, as the NH2-terminal residues. The first three residues favor N alpha-acetylation. Proteins that retain the initiator methionine commonly have a charged residue or methionine at the second position. Information on Hb South Florida and other hemoglobins coupled with this survey of primary sequence provides insights into the NH2-terminal processing of proteins.

Acetylation↗

PubMed2005

Interactions of cholesterol with lipid membranes and cyclodextrin characterized by calorimetry.

Interactions of cholesterol (cho) with different lipids are commonly believed to play a key role in the formation of functional domains in membranes. We introduce a novel approach to characterize cho-lipid interactions by isothermal titration calorimetry. Cho is solubilized in the aqueous phase by reversible complexation with methyl-beta-cyclodextrin (cyd). Uptake of cho into the membrane is measured upon a series of injections of lipid vesicles into a cyd/cho solution. As an independent assay, cho release from membranes is measured upon titrating lipid/cho mixed vesicles into a cyd solution. The most consistent fit to the data is obtained with a mole fraction (rather than mole ratio) partition coefficient and considering a cho/cyd stoichiometry of 1:2. The results are discussed in terms of contributions from 1), the transfer of cho from cyd into a hypothetical, ideally mixed membrane and 2), from nonideal interactions with POPC. The latter are exothermic but opposed by a strong loss in entropy, in agreement with cho-induced acyl chain ordering and membrane condensation. They are accompanied by a positive heat capacity change which cannot be interpreted in terms of the hydrophobic effect, suggesting that additive-induced chain ordering itself increases the heat capacity. The new assays have a great potential for a better understanding of sterol-lipid interactions and yield suggestions how to optimize cho extraction from membranes.

Calorimetry↗

PubMed1985

Characterization of proteoglycans from adult bovine tendon.

Proteoglycans were extracted in good yield from the proximal, fibrous portion of adult bovine tendon with 4 m guanidine HCl. They comprise less than 1% of the dry weight of the tissue. Using CsCl density gradient centrifugation, gel chromatography, and ion exchange chromatography, two populations of proteoglycans were separated and purified from other tissue proteins. One was a large, chondroitin sulfate proteoglycan with high buoyant density in CsCl. This component appeared to be composed of two or three subpopulations as detected by agarose/polyacrylamide electrophoresis, although they could not be effectively separated from one another for individual characterization. As a group, the large proteoglycans eluted from Sepharose CL-2B with Kav from 0.1-0.5 and their core protein had Mr greater than 200,000 with high contents of glutamic acid, serine, and glycine. The glycosaminoglycan chains had a weight average Mr of 17,000 and more than 98% of the uronic acid was glucuronic acid. This group comprised only 12% of the total proteoglycan of the tissue. The other 88% of the proteoglycans appeared to represent one group of small molecules that eluted from Sepharose CL-2B at Kav = 0.70. They demonstrated buoyant densities in a CsCl gradient ranging from greater than or equal to 1.51 to 1.30 g/ml. Their core protein had an apparent Mr = 48,000 following removal of the glycosaminoglycan chains by digestion with chondroitinase ABC. This core protein had a particularly high content of aspartic acid/asparagine and leucine. The glycosaminoglycan chains had a weight average Mr of 37,000 and were dermatan sulfate containing 73% iduronic acid. Those molecules found at highest buoyant density appeared to have additional glycosaminoglycan chains that were shorter. Proteoglycans were also extracted from the pressure-bearing distal region of this tendon, where contents of proteoglycan per wet weight of tissue were 3-fold higher and as much as 50% of this was as large as the large proteoglycans from the proximal tissue. Preparations of large proteoglycans from both tendon regions contained molecules capable of interacting with hyaluronic acid.

Amino Acids↗

PubMed1975

Intramolecular addition of the riboflavin side chain. Anion-catalyzed neutral photochemistry.

The presence of higher (greater than 0.2 M) concentrations of divalent anions A2- (hydrogenphosphate, sulfate) is found to accelerate as well as to change entirely the course of riboflavin photolysis: instead of 10-dealkylation to yield lumichrome, intramolecular addition of the 2'-hydroxyl group is found to occur at the peri-position C(9). The reaction is analogous to the "photohydration" of the flavin nucleus in the cationic state as described by Schöllnhammer and Hemmerich [Eur. J. Biochem. (1974) 44, 561-577]. The final product of the new addition reaction arises from autoxidation of a dihydroflavin intermediate and exhibits the structure. It is thus representative for a new class of flavins ("cyclo-dehydroflavins"). Earlier reports on "anomalous" flavin photodegradation products absorbing around 410 nm [Holmström (1964) Ark. Kem. 22, 281; Massey and Atherton (1962) J. Biol. Chem 237, 2965] are readily explained. The reaction is found to depend strictly on the presence of a nucleophilic function in the N(10)-side chain, e.g. N(10)-CH2-C(OH)RR' or even N(10)-(CH2)2-SO3-. Quenching experiments suggest that the new reaction occurs via the singlet state 1FLox while the normal photolysis is mediated by the triplet 3Flox. The new photoaddition is though to occur via a Flavin-A2- complex which creates sterically favorable conditions for C(9)/O(2'alpha)-interaction.

Hydrogen-Ion Concentration↗

PubMed1986

Structure of turnip crinkle virus. III. Identification of a unique coat protein dimer.

The minor structural protein (p80), found in about one copy per virion in turnip crinkle virus (TCV), is shown by amino acid analysis and peptide mapping to be a covalent dimer of the major coat protein (p40). The covalent linkage occurs near the N termini of the crosslinked chains. These data suggest that TGV and related viruses contain 178 copies of p40 (89 non-covalent dimers) and one copy of p80 (covalent dimer of two additional p40 chains). The presence of p80 in the salt-stable RNA-protein complex formed when TCV dissociates, as described in an accompanying paper, indicates that the covalent modification affects binding to RNA. We suggest that p80 might be the final dimer to be incorporated into the shell and that it might also be the site for initiation of uncoating.

Amino Acids↗

PubMed2006

Additive benefits of long-chain n-3 polyunsaturated fatty acids and weight-loss in the management of cardiovascular disease risk in overweight hyperinsulinaemic women.

BACKGROUND: Obesity, inflammation, insulin resistance and cardiovascular disease (CVD) risk are inter-related. Both weight-loss and long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) are independently known to reduce metabolic risk, but the combined effects are unclear. OBJECTIVE: This study examines whether addition of LC n-3 PUFA to a low fat/high carbohydrate weight-loss programme results in greater improvements in inflammation, insulin sensitivity and CVD risk, than weight-loss alone. DESIGN: One hundred and sixteen overweight insulin-resistant women entered a 24-week randomised intervention study. Thirty-nine women were randomised to a weight-loss programme, with LC n-3 PUFA (WLFO), 38 to a weight-loss programme with placebo oil (WLPO), and 39 to receive placebo oil, with no weight-loss programme (control). RESULTS: Ninety-three women completed the study (35 WLFO, 32 WLPO and 26 control), with significant weight-loss in WLFO (10.8+/-1.0%) and WLPO (12.4+/-1.0%) compared to the control group (P<0.0001). The WLFO, but not WLPO or control group, showed significant increases in adipose tissue LC n-3 PUFA (0.34+/-0.20 vs 0.17+/-0.10 and 0.16+/-0.10 %DHA, P<0.0001). Weight-loss showed significant improvements in insulin sensitivity (P<0.001), lipid profile (triglycerides P<0.05) and inflammation (sialic acid P<0.05). Time*group effects showed significant decreases in triglycerides (P<0.05) and increases in adiponectin (P<0.01) with LC n-3 PUFA, in the WLFO vs WLPO groups. CONCLUSIONS: Weight-loss improved risk factors associated with CVD, with some additional benefits of LC n-3 PUFA on triglycerides and adiponectin. Given the current low dietary intake of LC n-3 PUFA, greater attention should be given to increase these fatty acids in the treatment of obesity.

Adipose Tissue↗

PubMed1999

Co-secretion of two distinct kappa light chains by the mu-9 hybridoma.

Mu-9 is a monoclonal antibody (MAb) specific for the CSAp antigen (Ag) expressed by colorectal cancers. By using variable (V)-region-specific primers, the respective VH and VL sequences of Mu-9 were polymerase chain reaction (PCR)-amplified. However, chimeric Ab (cMu-9-1) constructed from these PCR-amplified V sequences failed to bind the CSAp Ag. Although the light chain of murine Mu-9 was not glycosylated, that of cMu-9-1 was found to be O-glycosylated, as confirmed by reducing SDS-PAGE analyses, glycoprotein blotting and O-linked specific deglycosylation studies. Removal of O-linked oligosaccharides either by enzymatic digestion or by blocking O-glycosylation with a specific inhibitor did not restore the immunoreactivity of cMu-9-1, indicating that light chain O-glycosylation was not the cause for lack of immunoreactivity. We reported earlier that screening of a Mu-9 cDNA library uncovered the presence of an additional light chain sequence that was later proven to be the authentic light chain of Mu-9. Analyses of the cDNA sequence encoding the nonimmunoreactive light chain, however, revealed no defects that would preclude the sequence from being translated and secreted by the murine hybridoma. By adapting the Mu-9 hybridoma culture to serum-free conditions, we confirmed the secretion of low levels of O-glycosylated light chain. The biological significance of the O-glycosylation as well as the cosecretion of both light chains with respect to allelic exclusion are discussed.

Amino Acid Sequence↗