Ultracentrifugal Patterns Research Articles

Thermal stability of pyrrolidone carboxyl peptidases from the hyperthermophilic Archaeon, Pyrococcus furiosus

The temperature adaptation of pyrrolidone carboxyl peptidase (PCP) from a hyperthermophile, Pyrococcus furiosus (Pf PCP), was characterized in the context of an assembly form of the protein which is a homotetramer at neutral pH. The Pf PCP exhibited maximal catalytic activity at 90-95 degrees C and its activity was higher in the temperature range 30-100 degrees C than its counterpart from the mesophilic Bacillus amyloliquefaciens (BaPCP). Thermal stability was monitored by differential scanning calorimetry (DSC). Two clearly separated peaks appeared on the DSC curves for Pf PCP at alkaline and acidic pH. Using the oxidized Pf PCP and two mutant proteins (Pf C188S and Pf C142/188S), it was found that the peaks on the high and low temperature sides of the DSC curve of Pf PCP were produced by the forms with an intersubunit disulfide bridge between the two subunits and without the bridge, respectively, indicating the stabilization effect of intersubunit disulfide bridges. The denaturation temperature (Td) of Pf PCP with intersubunit disulfide bridges was higher by 53 degrees C at pH 9.0 than that of BaPCP. An analysis of the equilibrium ultracentrifugation patterns showed that the tetrameric Pf C142/188S dissociated into dimers with decreasing pH in the acidic region and became monomer subunits at pH 2.5. The heat denaturation of Pf PCP and its two Cys mutants was highly reversible in the dimeric forms, but completely irreversible in the tetrameric form. The Td of Pf C142/188S decreased as the enzyme became dissociated, but the monomeric form of the protein was still folded at pH 2.5, although BaPCP was completely denatured at acidic pH. These results indicate that subunit interaction plays an important role in stabilizing PCP from P. furiosus in addition to the intrinsic enhanced stability of its monomer.

Review of human studies evaluating individual dietary responsiveness in patients with hypercholesterolemia

Individual variation in the low-density-lipoprotein (LDL)-cholesterol response to a cholesterol-lowering diet has been well documented in inpatient and outpatient diet studies. This variation could be due to both clinical and biological factors. Clinical factors include adherence to dietary changes and changes in body weight. Biological factors include specific changes in dietary composition, initial serum cholesterol concentrations, presence of excess body weight, the fractional catabolic rate of LDL with a diet high in saturated fatty acid, the presence of specific isoforms of apoprotein E and apoprotein A-IV, changes in the gene encoding apoprotein B or the apoprotein A-I promoter region, and the ultracentrifugation pattern of LDL lipoproteins. Work exploring the metabolic basis for individual variation in responsiveness to a cholesterol-lowering diet is in its infancy. Careful studies controlling for the clinical influences of responsiveness are needed so that true biological determinants of response can be uncovered.

A SIMPLE, RAPID AND SIMULTANEOUS PREPARATION OF GLANDLESS COTTENSEED 7S AND 11S PROTEIN FRACTIONS AND CHARACTERIZATION OF SOME PHYSICOCHEMICAL PROPERTIES

A simple and rapid method for simultaneous preparation of individual protein fractions from glandless cottonseed storage proteins was developed. With gel filtration chromatography, using Sephacryl S-300 HR and 10% NaCl solution as an eluent, 3 fractions, FI, FII, FIII were obtained. FII and FIII produced single peaks by gel filtration rechromatography and anion exchange chromatography. FII and FIII showed both a single major and a barely noticeable minor band, respectively, on polyacrylamide gel electrophoresis. Analytical ultracentrifuge patterns showed impurites less than 2% in FII and a single symmetrical peak for FIII. Sedimentation coefficients were computed to be 10.7S and 6.8S for FII and FIII, respectively; molecular weights by osmometry were 2.39 × 105 and 1.40 × 105 g/mole for FII and FIII, respectively. Both fractions were high in acidic and low in sulfur-containing amino acids, and contained phytate and gossypol at less than 10 and 2 ppm, respectively.

Effect of acetylation and succinylation on the physicochemical properties of winged bean (Psophocarpus tetragonolobus) proteins

Winged bean flour was acylated to various degrees by acetic and succinic anhydrides. Changes in physicochemical properties such as PAGE, fluorescence spectra and ultracentrifuge patterns of acylated proteins were measured. Acetylation and succinylation dissociated the proteins of winged bean to lower mol. wt. proteins. The extent of dissociation depends upon the degree of acetylation/succinylation. Succinylation dissociates winged bean proteins to a greater extent than acetylation.

Experimental nephrotic syndrome: removal and tissue distribution of chylomicrons and very-low-density lipoproteins of normal and nephrotic origin

Lymph chylomicrons and plasma VLDL, 14C-labelled in vivo, were isolated from normal and nephrotic rats and injected into normal or nephrotic recipients. In normal recipients, the half-life of chylomicrons of nephrotic vs. normal origin was significantly longer (5.2 ± 0.5 vs. 3.5 ± 0.4 min −1). The nephrotic chylomicrons were larger in size, deficient in apo-E and apo A-I, rich in triacylglycerol and cholesterol, but poor in phospholipids, indicating that factors related to composition affected their removal. The half-life of nephrotic vs. normal VLDL, given to normal recipients, was unexpectedly shorter, (4.5 ± 0.2 vs. 5.8 ± 0.2 min −1). The nephrotic VLDL were also triacylglycerol- and cholesterol-rich and phospholipid-poor, but had a large diameter spread and contained a dense fraction according to the zonal ultracentrifugation pattern, suggesting the presence of faster removable IDL-like particles. When nephrotic rats received normal particles, a pronounced removal delay was seen, paralleling the extent of plasma triacylglycerol elevation. The half-life of chylomicrons was 8.3 ± 1.4 and 15.2 ± 2.5 min −1 in moderately and severely nephrotic rats, respectively, that of VLDL was 11.72 ± 2.1 and 37.8 ± 7.1 min −1 correspondingly. The chylomicron-triacylglycerol uptake was reduced both by adipose tissues and muscles of normal or nephrotic recipients, with some increase in entry into lungs, kidneys and spleen. Tissue distribution patterns of VLDL-triacylglycerol was similar to that of chylomicrons, except that the liver took up approx. 90% of the label. The low share of triacylglycerol uptake by tissues rich in lipoprotein lipase indicates that the activity of this enzyme was unlikely to limit the rate of removal. Lipoprotein lipase activity in adipose tissue and heart was slightly decreased in moderately nephrotic rats and declined only by approx. 35% in severely nephrotic ones. These results indicate that the removal defect in nephrosis seems to be due, in part, to changes in the composition of triacylglycerol-rich particles, compromising their accessibility to lipolysis and, in part, to their abundance, saturating the lipolytic capacity.

Effect of pressure treatment on depolymerization of fish F-actin.

The effects of pressure treatment (1, 000 atm-5, 000 atm) on depolymerization of F-actin from flying fish, sardine, and walleye pollack muscles were examined in connection with the repolymerizing ability after the release of pressure. It was shown that the relative viscosity of F-actins decreased rapidly over 2, 000 atm and the inactivation of actomyosin Mg-ATPases from native myosin plus pressure-treated F-actin occurred. However, there was no appreciable difference in ΔV value of F-actin by pressure treatment among fish species. Ultracentrifugal patterns of pressure-treated F-actin showed the transformation into G-actin. Repolymerization of their pressure-treated actins could be observed at 15°C Cor 25°C. The addition of 0.5mM ATP gave a rapid repolymeri-zation of actins.

Symptom Regulation Induced by Chicory Yellow Mottle Virus Satellite‐Like RNA

AbstractCYMV‐T, CYMV‐C and CYMV‐RS are three strains of CYMV, a nepovirus isolated from chicory in Southern Italy. They are serologically indistinguishable, but display different electrophoretic and analytical ultracentrifugation patterns. In fact the RNAs obtained from CYMV‐T, when analyzed in 2.4% polyacrylamide cylindrical gels, showed the presence of a 170,000 mol. wt. satellite‐like RNA (CYMV‐T Sat RNA) and several other RNAs, whereas CYMV‐RS gave only the genomic RNAs and CYMV‐C, in addition, some ofthe RNAs present in CYMV‐T but not the Sat RNA.When these three strains were assayed on Nicotiana glutinosa L., CYMV‐C and CYMV‐RS elicited typical necrotic rings, whereas CYMV‐T infections were symptomless. The conclusions were drawn that CYMV‐T Sat RNA is another low mol. wt. RNA able to display viral disease regulation and that CYMV‐T, CYMV‐C and CYMV‐RS could represent an example of natural oscillation among different stages of RNA satellite emergence.

Temperature conditions for the frozen storage of representative marine products in Japan

Abstract Four representative seafoods in Japan were examined for quality changes during frozen storage up to 1 year, and reasonable temperature conditions for their frozen storage were determined. Tuna meat was stored at ‐20 ∼ ‐80°C for 1 year and its quality changes were followed by using parameters such as the metmyoglobin to total myoglobin ratio, water‐holding capacity, and pH. Ikura, a salted product of salmon eggs, was stored frozen. Quality changes were followed by using the following parameters: toughness of the egg membrane, carotenoid content, and TBA value. Surimi, meat paste from Alaska pollack, was kept frozen, and the quality changes were followed by analyzing protein composition, SDS‐gel electrophoretic and ultracentrifugal patterns, and the gel strength of kamaboko processed therefrom. Finally, prawn was stored frozen. At selected time intervals, the meat was analyzed for changes in water‐holding capacity, pH, tyrosine content, protein composition, and SDS‐gel electrophoretic pattern. From...

Metabolic interrelationships of HDL subclasses.

Levels of plasma HDL are determined by a complex array of metabolic processes involving synthesis, transfer, recycling, and tissue uptake of individual apoprotein and lipid components1. At equilibrium, these components are organized within a variety of particulate forms, and detailed understanding of HDL metabolism requires consideration of factors responsible for this macromolecular heterogeneity. The first description of the HDL particle spectrum identified three major forms of HDL based on flotation rates (F°1.20) in the analytic ultracentrifuge2: HDL1, of F°1.20>9 and density overlapping with LDL; HDL2, of F°1.20 3.5–9 (d 1.063–1.125 g/ml), and HDL3, of F°1.200–3.5 (d 1.125–1.200 g/ml). Figure 1 shows the analytic ultracentrifuge pattern of HDL2 and HDL3 in a representative normal subject, as well as the HDL profile as revealed by zonal ultracentrifugation3 and electrophoresis of HDL in native polyaerylamide gradient gels4. Each of these procedures has revealed further heterogeneity within the HDL2 and HDL3 density subclasses. In the case of gradient gel electrophoresis, heterogeneity is manifest as multiple electrophoretic bands which have been shown to represent distinct HDL subspecies of differing particle size.KeywordsImmunoaffinity ChromatographyPlasma High Density LipoproteinHigh Density LipoFractional Catabolic RateFlotation RateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Subunit dissociation of Busycon canaliculatum hemocyanin

The hemocyanin of the channeled whelk, Busycon canaliculatum, is a multisubunit protein with a molecular weight close to 9 ṡ10 6. The increase in pH above neutrality and the addition of 0–5 M urea and 0–2 M GdnHCl is found to dissociate the whole molecules to half-molecules and smaller dimeric and monomeric fragments of one-tenth and one-twentieth mass of the parent hemocyanin. The molecular weight transitions investigated at constant protein concentration of 5 ṡ 10 −2 g ṡ 1 −1 show no clearly discernible plateau regions, where essentially only half-molecules and one-tenth molecules are present. The ultracentrifugation patterns in much of the dissociation region produced by urea at pH 6.9 suggests the presence of three distinct components consisting of whole molecules, half-molecules and largely one-tenth molecular weight fragments. At pH 8.2 and higher, where whole molecules are largely absent the effects of urea on the dissociation of half-molecules to tenths and tenth-molecules to twentieth molecule was investigated by means of light scattering. Analysis of the urea data based on a decamer to dimer and dimer to monomer scheme of dissociation used in our earlier studies gave apparent estimates of about 90 amino acid groups at the contact areas of the dimers in the half-molecules and 110 groups at the monomer contacts forming the dimers. The latter relatively large estimate of groups suggests that the dissociation of the tenth molecules or dimers must occur by longitudinal splitting of the contact areas along both the folded domains and the connecting chain segments of the twentieth molecules. Circular dichroism, absorbance and viscosity data suggest that the secondary structure and conformation of the folded domains of the hemocyanin subunits are largely retained at both high pH and in 3–8 M urea solutions. The molecular weights at pH 9.0–10.6 and in 3–8 M urea are found to be (4.2–4.7) ṡ 10 5, close to one-twentieth of the mass of the parent hemocyanin. Denaturation and unfolding of the subunit domains is observed between 3 and 6 M GdnHCl solutions, as evidenced by the abolition of the characteristic copper absorbance in the neighborhood of 346 nm and the relatively pronounced changes in circular dichroism at 222 nm and intrinsic viscosity. The further decrease in molecular weights to about (2.6–3.2) ṡ 10 5, below one-twentieth of the mass of hemocyanin suggests the presence of hidden breaks or scissions in the polypeptide chains suffered during isolation, which become exposed as a result of complete unfolding in GdnHCl solutions. Studies by other investigators have shown that the molluscan hemocyanins are extremely susceptible to proteolysis during the process of isolation.

Quality changes in Alaska pollack meat paste ("surimi") during frozen storage.

Some attempts were made to find the reasonable conditions of frozen storage of Alaska pollack meat paste (“surimi”).Small blocks of Alaska pollack surimi were kept frozen at -20°, -30°, -40°, -60° and -80°C for one year and changes in muscle protein composition, SDS-polyacrylamide gel electrophoretic and ultracentrifugal sedimentation patterns of muscle protein fractions, and gel (kamaboko)-forming ability were followed at due intervals.At -20°C, myofibrillar proteins were gradually denatured, resulting in decreases of extractability and gel-forming ability, and in changes of ultracentrifugal pattern. At -30°C, denaturation of those proteins proceeded much more slowly than at -40°C. In contrast, no or little denaturation of myofibrillar proteins occurred below -40°C.It was concluded that -30°C is the most reasonable temperature for a short term storage up to several months, whereas -40°C is preferable for a long term storage up to one year.

Preliminary crystallographic data for the copper enzyme ascorbate oxidase

Ascorbate oxidase (EC 1.10.3.3) is a copper enzyme belonging to the group of so-called ‘blue oxidases’ together with laccases and ceruloplasmin. The enzyme, widely distributed in several plant species, catalyzes the oxidation of L-ascorbate, transferring the reducing equivalents to molecular dioxygen. The biological function of the enzyme is still in question. Ascorbate oxidase activity is highest in those parts of plants which grow faster; on the other hand some authors suggested a possible role of the enzyme in plant respiration [1]. The native enzyme is a non-covalent dimer, whose subunits (respectively 75,000 and 72,000 Mr) contain 8 Cu 2+ ions; these can be classified, according to their coordination environments, as of type-1, type-2 and type-3 [2, 3]. Ascorbate oxidase is known to undergo fully reversible association-dissociation phenomena. Its ultracentrifuge pattern changes as a function of pH and buffer media, while the spectroscopic properties and the activity towards ascorbate remain unchanged. Although the information available at present is not sufficient to fully elucidate the sequence of redox events which take place within the protein, there exist some evidence that the three classes of copper ions fulfil different functions. Type-1 copper is the primary site of electron acceptance; type-2 and type-3 coppers are implicated respectively in ascorbate and O 2 binding [4]. Ascorbate oxidase is thus an ideal model enzyme for the study of biochemistry and biophysics of vegetal copper proteins. In consideration of its physico-chemical properties, the elucidation of ascorbate oxidase three-dimensional structure may also contribute to the comprehension of the association-dissociation phenomena and of their biological significance. The protein employed for the crystallization experiments was purified from green zucchini squash according to the method of Avigliano et al. [5], showed absorption ratios A 280/A 610 = 25 ± 1, A 330/ A 610 = 0.8 ± 0.05 and had a turnover number of 5 × 10 5 mol/min. Several micro-buttons filled with a 15 mg/ml solution of the enzyme were used in parallel dialyses experiments against different buffers and precipitating agents, in the pH range 5–9. Under the following conditions the same characteristic blue crystals of the enzyme could be grown: 1. 1.8 M ammonium sulfate, at pH values 6.7 through 8.4 2. 1.0 M sodium citrate, at pH 7 3. 1.9 M potassium phosphate, at pH 7 The crystals obtained were subsequently used for a preliminary crystallographic. From the analysis of the diffraction pattern symmetry and of the systematic absences it was possible to conclude that ascorbate oxidase crystallizes in the orthorhombic space group P2 12 12 1 with unit cell edges a = 125.4, b = 189.8, c = 112.2 Å. The asymmetric unit can thus accommodate a dimer of the enzyme (Mr 294,000) and the (volume) solvent content of the crystals is 45%. The crystals diffract to 3.0 Å resolution; this crystalline modification is isomorphous with that reported by Ladenstein et al. [ 6] for the same enzyme, but grown under different physico-chemical conditions.

Functionality of Soy Proteins in Wheat Flour/Soy Isolate Doughs. I. Characterization of Isolates Prepared Using Different Isolation Procedures

Soy proteins prepared under laboratory conditions using different extraction media (water and alkali), different treatment in the separation of the isolated proteins (isoelectric precipitation and neutralization to form Ca, K and Na proteinates) and drying (freeze-, spray and drum drying) were subjected to chemical and physico-chemical testing in order to establish quantitatively the differences between their nature and their functional behaviour in protein supplemented wheat doughs. (Results of functionality tests will be reported in Part II.) Apart from chemical analysis (including reactive and total SH and SS groups) and N solubility tests, the isolates were compared on the basis of their gel filtration profiles and electrophoretic as well as ultracentrifugation patterns of their major globulin fraction. The tests revealed some consistent differences between the test proteins (e.g., higher SH and SS content in isoelectric protein than in proteinates, minor but consistent differences in the gel filtration profiles of the alkali and water extracted isolates, higher loose bulk density of the former); but water solubility and hydration capacity, measured in terms of both water absorption and retention, gave expectedly the most marked indication of sufficient variability in the nature of the isolated samples for further testing of their functionality.

Active form of pyridoxal phosphate in glycogen phosphorylase. Phosphorus-31 nuclear magentic resonance investigation.

The substrate analogue alpha-D-glucopyranosyl cyclic 1,2-phosphate has been confirmed to be a good competitive inhibitor of glycogen phosphorylases a and b isolated from rabbit muscle. Effects of tertiary and quaternary structure of the enzyme have been shown to be similar to those induced by the substrate glucose 1-phosphate and different from those of the coincidently binding inhibitor glucose. This information was obtained from study of the ultracentrifugation patterns of the enzyme-inhibitor complex and by determination of its effect on the binding constant for the activator AMP. 31P NMR investigation of the binding of this inhibitor to the enzyme has demonstrated that it both tightens the binding of the nucleotide activator and shifts the resonance of the phosphate group of the pyridoxal phosphate residue to a broad signal around 0 ppm. This situation is further reinforced in the presence of the second substrate, maltopentaose, giving a fully potentiated, but inactive, enzyme-substrate complex. This has not been studied previously by 31 P NMR. The active form of the pyridoxal phosphate (PLP), in the presence of substrates or their analogues, is not therefore a mobile dianionic phosphate as has been previously proposed. It may represent a tightly bound and constrained dianionic phosphate or possible a protonated phosphate in intermediate exchange. The implications of this finding are discussed.

Studies on the freeze denaturation of squid actomyosin.

Denaturation of squid actomyosin during frozen storage was studied by measuring solubility, viscosity, and ATPase activity, and by ultracentrifugal analysis and SDS-electrophoresis. The additive effect of sodium glutamate, well-known for its cryoprotective effect on the freeze denaturation of carp actomyosin, was also checked. When solutions (0.6 M KCI) or suspensions (0.05 M KCI) of the isolated squid actomyosin were stored at -20 ??, the solubility, reduced viscosity and ATPase activity decreased with the length of frozen storage. The ultracentrifugal patterns showed that aggregation proceeded during frozen storage. Evidently, sodium glutamate prevented the freeze denaturation of squid actomyosin, as in the case of carp actomyosin. When the mantle muscle of squid was freeze-stored at -20 ?? and extracted with 0.6 M KCI, the amount of soluble actomyosin extractable from the frozen meat and the ATPase activity of the actomyosin were decreased only slightly even after a long freezing period. This differed from the results with isolated actomyosin.

Ultracentrifugation of salt‐soluble proteins in ten legume species

AbstractThe ultracentrifugation patterns of the total salt‐soluble proteins in pea and northern bean showed four globulin fractions in flour proteins but only the 2S, 7S and 9S globulins were found in the isolates. Mung bean, lentil and lupin exhibited 2S, 7S and 11S globulins in flour and isolate proteins while chick‐pea, field‐pea, faba‐bean and soya‐bean proteins also contained the 15S fraction. Salt‐soluble proteins from lima bean were unique in their composition of 5S, 7S and 15S fractions. Only pea bean and lentil failed to show high proportions of the 1‐5S fraction in the flour proteins.

Chemical, biological and immunological characterization of separated electrophoretic components of human chorionic somatomammotropin (HCS).

Purified HCS preparations ofter show heterogeneity when assayed by electrophoresis, although they may be considered homogeneous according to other criteria (N-terminal amino acid analysis, gel filtration and ultracentrifugation patterns, etc.). Using DEAE-cellulose chromatography, the two main components corresponding to various degrees of hormone amidation were separated. The deamidation kinetic of the electrophoretically slower migrating component was studied and found to be sensitive to temperature and, to a lesser extent, to pH. Denaturing agents strongly increased the deamidation rate, while no effect was found by raising the ionic strength. No difference was evident between the two components and the parent hormone when compared (on a weight basis) in a specific HCS radioimmunoassay system. Even the precipitin reaction in agar gel with an anti-human growth hormone (HGH) serum did not show variations in cross-reactivity versus HGH. Moreover, groups of guinea pigs immunized with the single HCS components, gave antibodies reacting identically with the components and the parent HCS. The prolactin-like activity of the two components differed when determined by the pigeon crop-sac asay: the slower migrating component proved to be less active than the more deamidated one. On the other hand, the activity in two different radioreceptor assays (employing membranes from rabbit mammary gland and rat ventral prostate) was greater for the faster migrating component.

Dissociation of apolipoprotein A-I from porcine and bovine high density lipoproteins by guanidine hydrochloride

Dissociation of apolipoprotein A-I from pig and steer high density lipoproteins (HDL) deficient in apoA-II was determined by exposing native HDL fractions to 6 M guanidine hydrochloride (Gdn-HCl) at 37°C for periods from 5 min to 18 h. Bovine high density lipoprotein (HDL-B) was isolated at d 1.063–1.100 g/ ml while porcine high density lipoprotein (HDL-P) was isolated at d 1.125–1.21 g/ ml. Incubation for 5 min with Gdn-HCl resulted in a 45 and 3% loss of apoA-I from HDL-P and HDL-B, respectively. Exposure to the denaturant for 3 h resulted in a 75% loss of apoA-I from HDL-P and a 30% loss from HDL-B. Analytic ultracentrifugation patterns paralleled the degree of apoA-I dissociation from each HDL species. The initial flotation peak for HDLP shifted from F° 1.20 2.68 to F° 1.20 10.75 after 3 h exposure while HDL-B showed only a small shift from F° 1.20 8.30 to F° 1.20 8.96 after 3 h exposure. HDL-P particle diameter increased 25% after 5 min of Gdn-HCl treatment and large, flattened structures predominated after 3 h. There was no change in the size of HDL-B after 5 min exposure and only 16% increase in particle diameter after 3 h. The difference in behavior of HDL-B and HDL-P to Gdn-HCl exposure is discussed in terms of differences in apolipoprotein A-I amino acid composition, interaction of apolipoprotein A-I with phospholipids and the possible involvement of the cholesteryl ester core.

Influence of heating temperature on conformational changes of soybean proteins.

Changes of ultracentrifugal patterns of soybean proteins by heating up to 100°C were almost completed at 80°C at lower ionic strength and at 90°C at higher ionic strength. How-ever, changes in DTNB reactive sulfhydryl groups, sulfite reducible disulfide bonds, ultraviolet difference spectra and turbidity of the protein solutions were still observed at temperatures higher than 80 or 90°C. These results suggest that 11S protein dissociates into subunits at a temperature below 80 or 90°C, and that the conformations of these subunits can change at a temperature above 80 or 90°C. When heated at high ionic strength, the protein solution became turbid because of aggregation of proteins. SDS polyacrylamide gel electrophoresis showed that aggregated proteins separated by centrifugation as precipitates were formed from low-mole-cular-weight subunits of 11S protein and non-aggregated proteins remaining in the super-natant were from 7S protein and high-molecular-weight subunits of 11S protein.

Dyslipoproteinemia (a remnant lipoprotein disease) in uremic patients on hemodialysis

Plasma lipoproteins of uremie patients on hemodialysis were studied by chemical, electrophoretic, ultracentrifugal and electron microscopic techniques. Low-density lipoproteins ( d 1.006–1.063) isolated from the plasma of five patients who were on hemodialysis therapy for 1 to 54 months showed two or three midband lipoproteins (bands between pre-β and (β-lipoproteins) when studied by polyacrylamide gel electrophoresis. Correspondingly, two or three peaks were observed in the analytical ultracentrifugal patterns of the isolated low-density lipoproteins of these patients. Low-density lipoproteins of a plasma which showed three midband lipoprotein components on polyacrylamide gel electrophoresis and three peaks by analytical ultracentrifugal analysis were isolated and each midband lipoprotein subfraction was characterized. As demonstrated with the isolated lipoprotein subfractions, low-density lipoproteins of the patient consisted of Sf 13, Sf 10, and Sf 7 + Sf 6 low-density lipoproteins. The lipoproteins with the higher Sf rate (Sf 13) contained more triglyceride and less cholesteryl ester and showed a larger lipoprotein particle size than the other low-density lipoprotein subfractions, which properties are characteristics of the intermediate-density, remnant lipoproteins. These findings indicate that the previously-reported “broad-midband lipoprotein pattern” on polyacrylamide gel electrophoresis which was detected in 58% of hemodialysis patients is a result of the accumulation of the remnant or intermediatedensity lipoproteins.