Peak Elution Volume Research Articles

Reduced cholesterol efflux capacity of HDL particles from Alzheimer's disease patients is not related to differences in lipoprotein profiles.

High density lipoproteins (HDL) are primarily known for their critical role in regulating cellular cholesterol concentrations via their capacity to induce cholesterol efflux from cells. HDL are also carriers of apolipoprotein E (ApoE), which is the strongest known genetic risk factor for AD. The main objective of this study was to determine the cholesterol efflux capacity of HDL particles isolated from plasma of APOE genotyped AD patients vs. age-matched cognitively normal controls, and to characterize plasma lipoprotein profiles using size exclusion chromatography. HDL particles were isolated from plasma samples of 10 AD patients (n=5 APOE3/E3, n=5 APOE3/E4) and 5 cognitively normal controls (n=5 APOE3/E3) using sequential ultracentrifugation followed by size exclusion chromatography. FPLC chromatograms were processed to adjust baseline values and calculate area under the curve (AUC) for LDL, HDL, and albumin using UNICORN 5.0 software. AUCs were used to estimate the relative distributions of fractions, including small and large HDL, and peak elution volume was used to estimate particle size most abundant in each fraction. Cholesterol efflux capacity of the isolated HDL particles was determined in PBMC-derived macrophages using a fluorescently labeled cholesterol assay kit. HDL from AD patients had dramatically reduced cholesterol efflux capacity compared with controls (36.0% ± 1.2% vs. 26.0% ± 1.2%, P<0.0001), with no difference between AD patients by APOE genotype (APOE3/E3, 25.9% ± 0.9%; APOE3/E4, 26.5% ±1.3%; P=0.21). There were no significant differences in the relative distributions or average particle sizes of HDL, LDL, albumin, or large and small HDL between patients and controls. These results suggest neither the amount nor size distribution of HDL particles is adequate to detect the main difference driving the diminished cholesterol efflux capacity of HDL particles from AD patients. The results of this study support previous findings of decreased cholesterol efflux capacity of HDL in AD patients, and underscore the necessity for additional analyses to characterize the compositional differences driving this diminished functional capacity and to further understand HDL's role in AD pathology.

Retention of polypropylene stereoisomers in solvent gradient interaction chromatography on porous graphitic carbon as influenced by temperature and mobile phase composition

The behavior of isotactic, syndiotactic and atactic polypropylene stereoisomers on porous graphitic carbon (PGC) at different column temperatures is investigated with 1-decanol, decalin and decane as the adsorption promoting solvents using gradient interaction chromatography (SGIC). Column temperatures between 120 – 180 °C are investigated for the three adsorption promoting solvents with 1,2,4-trichlorobenzene (TCB) as the desorption promoting solvent. Owing to the different stereochemistry of the isomers, their interaction with the atomic level flat surface (ALFS) of porous graphitic carbon is observed to be different when injected from the three different adsorption promoting solvents. Atactic and isotactic polypropylene are not separable when 1-decanol is used as the adsorption solvent but can be separated from syndiotactic PP at column temperatures of between 120 – 180 °C. The three stereoisomers have almost similar elution volumes when decalin is used as the adsorption promoting solvent between 120 – 170 °C. Decane allows for both adsorption and desorption of the stereoisomers at distinct peak elution volumes at the studied column temperatures of 120 – 160 °C. Furthermore, it is shown that increasing the column temperature while maintaining other chromatographic conditions can either decrease or increase retention depending on the adsorption promoting solvent. More importantly, retention is influenced by adsorption conditions (temperature and adsorption promoting solvent) which may affect macromolecular conformations upon injection onto the PGC stationary phase. This is the first study on PP stereoisomers highlighting this behaviour.

Insoluble Aggregates and Protease-resistant Conformers of Prion Protein in Uninfected Human Brains

Aggregated prion protein (PrPSc), which is detergent-insoluble and partially proteinase K (PK)-resistant, constitutes the major component of infectious prions that cause a group of transmissible spongiform encephalopathies in animals and humans. PrPSc derives from a detergent-soluble and PK-sensitive cellular prion protein (PrPC) through an alpha-helix to beta-sheet transition. This transition confers on the PrPSc molecule unique physicochemical and biological properties, including insolubility in nondenaturing detergents, an enhanced tendency to form aggregates, resistance to PK digestion, and infectivity, which together are regarded as the basis for distinguishing PrPSc from PrPC. Here we demonstrate, using sedimentation and size exclusion chromatography, that small amounts of detergent-insoluble PrP aggregates are present in uninfected human brains. Moreover, PK-resistant PrP core fragments are detectable following PK treatment. This is the first study that provides experimental evidence supporting the hypothesis that there might be silent prions lying dormant in normal human brains.

Purification of cell culture‐derived human influenza A virus by size‐exclusion and anion‐exchange chromatography

A process comprising of size‐exclusion chromatography (SEC) and anion‐exchange chromatography (AEC) was investigated for downstream processing of cell culture‐derived influenza A virus. Human influenza virus A/PR/8/34 (H1N1) was propagated in serum‐free medium using MDCK cells as a host. Concentrates of the virus were prepared from clarified and inactivated cell culture supernatants by cross‐flow ultrafiltration as described before. SEC on Sepharose 4 FF resulted in average product yields of 85% based on hemagglutination (HA) activity. Productivity was maximized to 0.15 column volumes (cv) of concentrate per hour yielding a reduction in total protein and host cell DNA (hcDNA) to 35 and 34%, respectively. AEC on Sepharose Q XL was used to separate hcDNA from virus at a salt concentration of 0.65 M sodium chloride. Product yields >80% were achieved for loads >160 kHAU/mL of resin. The reduction in hcDNA was 67‐fold. Split peak elution and bimodal particle volume distributions suggested aggregation of virions. Co‐elution with hcDNA and constant amounts of hcDNA per dose indiciated association of virions to hcDNA. An overall product yield of 52% was achieved. Total protein was reduced more than 19‐fold; hcDNA more than 500‐fold by the process. Estimation of the dose volume from HA activity predicted a protein content at the limit for human vaccines. Reduction of hcDNA was found insufficient (about 500 ng per dose) requiring further optimization of AEC or additional purification steps. All operations were selected to be scalable and independent of the virus strain rendering the process suitable for vaccine production. Biotechnol. Bioeng. 2007;96:932–944. © 2006 Wiley Periodicals, Inc.

Structural basis for the inhibition of activin signalling by follistatin

The secreted, multidomain protein follistatin binds activins with high affinity, inhibiting their receptor interaction. We have dissected follistatin's domain structure and shown that the minimal activin-inhibiting fragment of follistatin is comprised of the first and second Fs domains (Fs12). This protein can bind to activin dimer and form a stable complex containing two Fs12 molecules and one activin dimer. We have solved crystal structures of activin A alone and its complex with Fs12 fragment to 2 A resolution. The complex structure shows how Fs12 molecules wrap around the back of the 'wings' of activin, blocking the type II receptor-binding site on activin A. Arginine 192 in Fs2 is a key residue in this interaction, inserting itself in between activin's fingers. Complex formation imposes a novel orientation for the EGF- and Kazal-like subdomains in the Fs2 domain and activin A shows further variation from the canonical TGF-beta family fold. The structure provides a detailed description of the inhibitory mechanism and gives insights into interactions of follistatin with other TGF-beta family proteins.

Dodecameric Structure of the Small Heat Shock Protein Acr1 from Mycobacterium tuberculosis

Small heat shock proteins are a ubiquitous and diverse family of stress proteins that have in common an alpha-crystallin domain. Mycobacterium tuberculosis has two small heat shock proteins, Acr1 (alpha-crystallin-related protein 1, or Hsp16.3/16-kDa antigen) and Acr2 (HrpA), both of which are highly expressed under different stress conditions. Small heat shock proteins form large oligomeric assemblies and are commonly polydisperse. Nanoelectrospray mass spectrometry showed that Acr2 formed a range of oligomers composed of dimers and tetramers, whereas Acr1 was a dodecamer. Electron microscopy of Acr2 showed a variety of particle sizes. Using three-dimensional analysis of negative stain electron microscope images, we have shown that Acr1 forms a tetrahedral assembly with 12 polypeptide chains. The atomic structure of a related alpha-crystallin domain dimer was docked into the density to build a molecular structure of the dodecameric Acr1 complex. Along with the differential regulation of these two proteins, the differences in their quaternary structures demonstrated here supports their distinct functional roles.

Potential of silica monolithic columns in peptide separations

The objective of the work described here was to evaluate the efficacy of silica monolith supports in high-speed reversed-phase liquid chromatography (RPLC) of peptides. This was done using a commercial Chromolith column with an octadecylsilane stationary phase and a tryptic digest of cytochrome c. Columns (100mm×4.6mm) were operated at mobile phase velocities ranging from 1ml/min (2.0mm/s) to 10ml/min (25mm/s). There was little noticeable change over this flow rate range in either resolution, peak elution volume, or analyte concentration in collected fractions. It was concluded that capillary columns in this silica monolith format would be particularly valuable in peptide separations for proteomics. There was, however, a small, but perceptible contamination of peaks at high mobile phase velocity with earlier eluting analytes. Based on the fact that peak shape did not change at high mobile phase velocity, it is suggested that this phenomena might be due to the presence of peptide conformers in structural equilibrium on the sorbent surface. When elution rate exceeds the rate of conformer interchange, conformers could elute as broadened or even separate peaks.

Mass‐Directed Normal‐Phase Preparative HPLC with Atmospheric Pressure Chemical Ionization Detection

A novel approach to auto‐purification of a wide variety of organic compounds is described. It is based on normal‐phase (NP) gradient high performance liquid chromatography (HPLC), performed on a 2 × 15 cm cyano column hyphenated with atmospheric pressure chemical ionization (APCI) source, and a single quad mass spectrometer (MS). A commercially available preparative HPLC–MS system, equipped with mass‐directed fraction collection capabilities, has been successfully used for NP purification of neutral, acidic, and basic pharmacologically active compounds. Samples of 10–100 mg were chromatographed in gradients of methanol in hydrophobic organic solvents, and collected using generic chromatographic, detection and fraction collection experimental parameters. “Smart” collection—one component–one collection vessel—with 90–95% recovery, was achieved by controlling injection volume and gradient slope and by adding acetic acid and diethylamine to the mobile phase to keep peak elution volumes below 50 mL. Auto‐collection of a solute was based on the main ion in its APCI–MS spectrum. The technique described has been also successfully used for chiral preparative HPLC applications and purification of non‐UV‐active compounds.

Effects of some dicarboxylic acids on the association of dissolved humic substances

Changes in molecular size distributions of four different humic materials were evaluated through high performance size-exclusion chromatography (HPSEC), before and after treating humic solutions with naturally occurring dicarboxylic (oxalic, malonic, succinic and glutaric) acids. Chromatograms of dissolved humic substances showed a decrease in peak absorbance as well as an increase in peak elution volume when the solution pH was lowered from 7 to 3.5 by addition of dicarboxylic acids before HPSEC analysis. The resulting reduction in molecular size is explained by the disruption of unstable humic superstructures into smaller-sized associations stabilized by the formation of strong intra- and inter-molecular hydrogen bonds among humic molecules. The extent of humic size variation was in the order: oxalic<malonic<succinic<glutaric acid. Dicarboxylic acids with an increasing number of C atoms and pKas, had progressively larger degrees of protonation which increasingly reduced the electrostatic repulsion from humic molecules. The less dissociated dicarboxylic acids enabled a closer contact with the hydrophobic domains of weakly bound humic superstructures and produced more extensive conformational rearrangements. Recognition of a process controlling the conformational structure of humic molecules by organic acids exuded in the soil solution by either plant roots or soil microbes may be important in understanding the role of humus in soil-plant interactions.

Examination of the Universality of the Calibration Curve of Size Exclusion Chromatography by Using Polymers Having Complex Macromolecular Architectures

The validity of the universal calibration curve (UCC) in size exclusion chromatography (SEC) was tested by using polymers having complex macromolecular architectures such as miktoarm stars ( w -stars) (PS) 2 PI, (PS) 2 PBd, (PI) 3 PS, (PS-PI) 2 (PI-PS) 2 , (PS)(PI)(PBd), (PS)(PI)(PBd)(P4MeS), H-shaped (PI) 2 PS(PI) 2 , and ~ -shaped (PS)(PI)PI(PS)(PI), as well as a model linear tetrablock copolymer of the PS-PI-PS-PI type, where PS is polystyrene, PBd polybutadiene, PI polyisoprene, and P4MeS is poly(4-methyl styrene). It was found that the universality of the relation of log(M[ m ]) vs. peak elution volume (V e ), where M is molecular weight and [ m ] is intrinsic viscosity, is valid even for these complex molecules. The determination of the molecular weight of a polymer by using the UCC is very sensitive to the molecular and compositional homogeneity of the sample.

Adsorption of Vapours of Some Organic Compounds on Surface of Iron-Substituted Layered Vanadyl Phosphate

Gas chromatographic measurement of specific retention volumes of vapours of selected groups of organic compounds has been used to determine differential molar enthalpy of adsorption of their molecules on the surface of layered vanadyl phosphate substituted with ferric ions having the composition of [Fe(H2O)]0.20(VO)0.80PO4. Various types of bonds of the molecules to the surface of the layered adsorbent including their probable orientation with respect to the layers have been discussed. It was observed a dependence of the specific peak elution volume and shape of chromatographic peak on the sample size in the cases of those compounds whose molecules are chemically bound to the adsorbent surface. A connection is pointed out between the adsorption strength of the organic molecules on the layered adsorbent and the tendency of the system to undergo intercalation reaction.

Purification, N-terminal sequencing and properties of wheat embryo acidic ribosomal A proteins with sequence similarity to calmodulin

A calmodulin-like protein (CALP) was purified from wheat embryo by a procedure successively involving precipitation by trichloroacetic acid and chromatography on DEAE-Sephacel, phenyl-Sepharcse CL-4B and Ultrogel AcA44. The CALP preparation elutes on gel filtration at a peak elution volume corresponding to a molecular weight of 100 000 and contains two major polypeptides P14 and P16 with molecular weights of 14 000 and 16 000, respectively. P14 and P16 were dissociated, purified by reversed phase HPLC and subjected to amino acid sequencing. The two subunits are structurally distinct, but nevertheless, have a high degree of identity with respect to each other and to acidic ribosomal ‘A’ proteins from wheat and other eukaryote sources. P14 and P16 both contain amino acid sequences similar to sequences in wheat embryo calmodulin (CaM) and related Ca2+-binding proteins. P14, P16 and similar eukaryotic acidic ribosomal ‘A’ proteins have N-terminal sequences that can be exactly aligned with the second half of CaM. The greatest similarity observed is with sequences of the amphipathic CaM F- and G-helices, the corresponding P14, P16 and ribosomal ‘A’ protein sequences also having the potential to form amphipathic helices. CALP and the isolated P14 and P16 polypeptides can mimic CaM in reactivating histone-inhibited wheat embryo Ca2+-dependent protein kinase. However, CALP does not substitute for CaM in activating avian myosin light chain kinase and does not bind Ca2+.

Determination and correction of peak broadening in size exclusion chromatography of controlled rheology polypropylene

AbstractThe peak broadening in size exclusion chromatography of seven commercial polystyrene (PS) standards with narrow molar mass distribution (MMD) and of 6–9 polypropylene (PP) fractions (M̄w/M̄n = 1.34–2.10) obtained by direct extraction was determined in four different column sets. The dependence of the Gaussian peak broadening parameter, σ2, on the peak elution volume was different for PS and PP. For a commercial grade of controlled rheology PP (CR‐PP) (Daplen PT55) with M̄w/M̄n &lt; 3 it was shown that disregard of the peak broadening effect leads to considerable errors in the MMD at low and higher molar mass and in the polydispersity parameter M̄w/M̄n. The same lot was studied in an Austrian National Research program for its physical propeties in processing and application and in a round‐robin test of IUPAC working party IV.2.2. on molecular characterization of commercial polymers. © 1994 John Wiley &amp; Sons, Inc.

Copper Induced Polymerization of Hemoglobin from the Ocean Pout, Macrozoarces americanus

Hemoglobins that polymerize are not uncommon among amphibians, reptiles, and elasmobranchs, but are rare among teleosts and humans. They are useful models for the study of protein structure, function, and molecular evolutionary relationships. The freshwater teleost Hoplias malabarica (I), the marine teleost Lophius americanus (2), and the clown fish, Amphiprion (3) are the only bony fishes reported to have hemoglobins that polymerize. Hoplias and Lophius polymerize by forming intermolecular disulfide bonds, while the polymerization mechanism for the clown fish is, as yet, unknown. Among humans, hemoglobins Ta-Li, Mississippi, and Pot-to Alegre (4, 5, 6) have a single mutation involving the substitution of a cysteine residue at different loci on the globin chain. We now report that the ocean pout has a single hemoglobin with six sullhydryl groups per tetramer and polymerizes, in vitro, after oxidation with potassium ferricyanide (K,Fe(CN),) or cupric chloride (CuClJ. Procedures for hemoglobin purification by DE-52 cellulose chromatography, molecular weight estimations by gel filtration on G100 columns, and urea gel electrophoresis for globin subunit analysis have been described (2). Hemoglobin was incubated with a twoto threefold molar excess of CuCIZ for 15 min in an ice bucket. The excess copper was removed by dialysis or by gel filtration from Sephadex G-25 columns equilibrated with 0.1 M K-PO., buffer, pH 7.4. Thereafter 20-40 mg of the hemoglobin was applied to and eluted from G100 columns. One-ml fractions were collected and the absorbance of each measured at 540 nm. The approximate polymer molecular weight was estimated from the elution volume of the peak tube. Hemoglobin solutions (0.52.0 g/%) were also oxidized by adding l-3 mg of potassium ferricyanide per ml of hemoglobin. Iodoacetamide (IAA)-alkylated hemoglobin ( 15 rmoles/mg hemoglobin) was dialyzed overnight, centrifuged, and subsequently treated with CuC12. In a separate xperiment, a 60-fold molar excess of beta-mercaptoethanol (B-ME) was added to CuCl*-treated hemoglobin, incubated for 1 h, and dialyzed for 3 h before G100 chromatography. Untreated hemoglobin and hemoglobin treated with CuCIZ alone served as controls and were dialyzed for the same period. The gel filtration profile of known molecular weight proteins is shown in Figure 1 A. The inset graph is a plot of the log of the molecular weight of each standard versus the elution volume of the peak tube. The linear relationship indicates that the peak tube elution volume provides a reasonable stimate of the protein molecular weight between 16,000 and 150,000 Da. (The molecular weight fractionation range for Sephadex G-100 is 4 X 10’ and 1.5 X 105.) .The effect of CuCl* on pout hemoglobin is shown in Figure 1 B. In the absence of the cation, the peak tube eluted at a volume comparable to human hemoglobin, suggesting anormal molecular weight for pout hemoglobin of approximately 60,000. The addition of CuC12 results in a polymer with a minimum molecular mass of 100 to 155 kDa, which corresponds to aggregates of, perhaps, two to three tetramers. Cupric-chloride-induced polymer formation may be inhibited by prior incubation with IAA (Fig. 1C). Hemoglobin alkylated with IAA elutes at the same volume as normal pout and human hemoglobin, but in the absence of IAA, cupric-chloride-induced

Displacement effects in large‐scale chromatography?

Displacement effects in large-scale (total column volume v(t) = 150 L) and preparative ion-exchange chromatography purifying human erythrocyte superoxide dismutase are described in the present article. The biomolecules are eluted in a very small peak elution volume (<0.2 v(o)) behind the salt wave using a step gradient. The theoretical peak width and retention behavior are calculated according to the model of Yamamoto. The theoretical values are then compared with the experimental data. There was a difference observed between the elution type I (also called fronting) and the experimentally obtained elution. Some instructions are given on how to achieve these phenomenona because a beneficial effect in respect to resolution and recovery of a biomolecule is observed.

Characterization of Polyvinylchloride by Size Exclusion Chromatography. I. Concentration Dependence of Axial Dispersion Observed in Size Exclusion Chromatography Coupled With Light Scattering

Abstract A comparative study on the axial dispersion in size exclusion chromatography was carried out on sample solutions with narrow molar mass distribution of polyvinylchloride (Mw=12000–96300 g/mol; Mw/Mn=1.14–1.25) and polystyrene (Mw=9000–1130000 g/mol Mw/Mn=1.04–1.08) in tetrahydrofuran. Determination of the axial dispersion parameter [Otilde] was accomplished by two independent methods for simultaneous calibration of separation and axial dispersion. For polystyrene, a slight dependence of [Otilde] on the peak elution volume was found as postulated in literature. At low concentration, there is a good agreement between [Otilde] measured for polystyrene (PS) and polyvinylchloride (PVC). Raising the concentration by a factor of 3, an increase of [Otilde] by about 25 % was found for PVC. The method of universal calibration proved to be applicable independent of concentration, when [η] =1.6 × 10−4 M0.706 dl/g for PS and [η] =1.6. × 10−4 M0,77 dl/g for PVC is used.

Study on the Concentration Effects in Gel Permeation Chromatography. Ii. a Model Theory of Concentration Effects for Polydispersed Polymers

Abstract In this paper a model theory of concentration effects for polydispersed polymers was presented. It is based these facts and assumptions that the total concentration effects are considered as the summation of the individual concentration effect, that each effects have also been explained as the consequence of both the reduction of hydrodynamic volumes and the viscosity phenomena of each species, and the entanglements between the macromolecules are negligeable. The relationships between the concentration of injected solutions with the hydrodynamic volumes, the elution volumes and the polydispersed index of hydrodynamic volumes were derived from this model theory. It can predict quantitatively the effects of concentration on the shift of peak elution volumes, the axial spreading and the skewing effects for polydispersed polymers.

Synthesis and characterization of styrene- b-dimethylsiloxane diblock and styrene- b-isoprene- b-dimethylsiloxane triblock copolymers

Poly(styrene- b-dimethylsiloxane) (PS-PDMS) diblock and poly(styrene- b-isoprene- b-dimethylsiloxane) (PS-PI-PDMS) triblock copolymers have been synthesized by living anionic sequential addition polymerization in tetrahydrofuran as solvent with n-BuLi as initiator. These copolymers were characterized by gel permeation chromatography (GPC), membrane osmometry, viscometry, nuclear magnetic resonance (NMR) spectroscopy, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The universal calibration curve of [η] M w vs GPC peak elution volume in methyl ethyl ketone for polystyrene (PS) and poly(dimethylsiloxane) (PDMS) standards was not unique suggesting that this method cannot be used for the calculation of true molecular weights of these diblock copolymers. Number-average molecular weights ( M n ) of the diblock copolymers were computed from their uncorrected GPC chromatograms using log M vs elution volume calibration curves of PS and PDMS in combination with the following equation: log M block = W PS log M PS + W PDMS log M PDMS where W PS and W PDMS are the weight fractions of PS and PDMS in the block copolymer ( W PS + W PDMS = 1). For M n < 4 × 10 4 , the calculated values were close to those measured experimentally. Micelles composed of PS-PDMS diblock copolymer formed in heptane were studied using SAXS. Radii of gyration of these micelles varied as the 1 3 power of the block copolymer molecular weight. SAXS measurement of the toluene cast films of the PS-PI-PDMS triblock copolymer yielded lamellar thickness of 54 nm. This value was larger than that (18.5—35 nm) obtained with TEM.

Comparison of Copper Metabolism between Brindled Mice and Dietary Copper-Deficient Mice Using 67Cu

Studies with 67Cu were conducted in suckling mice to differentiate between abnormal copper metabolism due to inadequate copper levels and that due to genetic factors. Brindled (Mobr/y) mice were compared to their normal brothers (Mo+/y) as well as to suckling mice that were copper-deficient (-Cu) because their dams were consuming a copper-deficient diet and a fourth group of suckling mice that served as dietary controls (+Cu). Male mice were injected with 67Cu when 8 days of age and were killed 3 days later. Whole-tissue 67Cu analysis revealed major labeling differences between the four groups, although the response in +Cu and Mo+/y animals was similar. Of seven tissues examined, liver accounted for the greatest percentage of 67Cu in +Cu (39%) and Mo+/y (39%) mice, and, to a lesser extent, in -Cu (7.6%) offspring, whereas kidney was highest for Mobr/y mice (10.5%). The labeling pattern for -Cu mice demonstrated an enrichment of 67Cu (counts per minute per milligram tissue) for all tissues with the exception of liver, compared to either +Cu or Mo+/y mice. Mobr/y mice showed an enrichment of 67Cu only kidney and bowel. Gel filtration chromatography was carried out on cytoplasmic extracts from liver, kidney and brain for all four groups. Three peaks were labeled: peak 1, void volume; peak 2, Ve:Vo = 1.59; peak 3, Ve:Vo = 2.24, where Ve is peak elution volume and Vo is void volume. Liver, kidney and brain cytosol of -Cu mice showed that more 67Cu was associated with a functional copper pool (peak 2, superoxide dismutase) rather than a storage pool (peak 3, metallothionein) compared to cytosol from +Cu or Mo+/y mice. In Mobr/y mice, more 67Cu was found with peak 3 than with peak 2, even in liver and brain, which are tissues that are low in total copper. Data indicate that the metabolism of copper in Mobr/y mice is different from -Cu mice.

Solvation and Adsorption Effects in Gel Permeation Chromatography

Abstract Saturated hydrocarbons are generally eluted according to molecular volumes in gel permeation chromatography (GPC). Other compounds, containing polar groups such as hydroxyl and carbonyl groups, deviate from the molecular volume/elution count relationship which is prepared using saturated hydrocarbons. The deviation is more or less observed regardless of the kinds of eluents. In this paper, this problem is investigated in detail with respect to infrared(IR) and proton magnetic resonance(NMR) spectra, and concentration dependences of peak heights and elution volumes in GPC. IR and NMR spectra reveal that alcohols, ketones and esters are strongly solvated by eluent molecules such as chloroform and tetrahydrofuran(THF). The solvation effect leads to faster elution for these compounds than expected for aliphatic hydrocarbons. On the other hand, the concentration dependences of elution counts and peak heights prove the adsorption of amines on polystyrene gel in chloroform. In fact, the elution rates of...