Separation of molecular species of lipoprotein lipase from adipose tissue

When NH(4)OH-NH(4)Cl extracts of adipose acetone powder were applied to agarose gel chromatography columns, two peaks of lipoprotein lipase were eluted. The first activity peak (LPL(a)) was eluted with an elution volume of a protein of molecular weight approximately five times that of the second (LPL(b)). Addition of heparin to the eluted fractions markedly stimulated activity of LPL(a), but suppressed that of LPL(b). Both lipases had the characteristics that distinguish lipoprotein lipase from other tissue lipases: a requirement for serum for substrate activation, inhibition by 1 m NaCl, and an alkaline pH optimum (pH 8.0). It is concluded that these fractions represent two species of lipoprotein lipase.     

Purification and biologic properties of fibroblast somatomedin

Cultured human fibroblasts produce a peptide growth factor that cross-reacts with antisera to human somatomedin-C (Sm-C). To determine the identity of this species and compare its molecular properties to pure Sm-C, 2 liters of conditioned medium derived from human fibroblast monolayers were concentrated (X10) by ultrafiltration. The concentrated conditioned medium was purified further by CM-Sephadex ion-exchange chromatography. Following elution in 1.0 M NaCl, pH 8.0, the active material was purified by gel filtration on Sephadex G-150. The active fractions which eluted at Kd 0.45 (Mr estimated at 32,000) were further purified by isoelectric focusing. Two peaks of activity electrofocused at pI 5.4 and 7.2, respectively. The pI 5.4 peak contained only binding protein activity. The active fractions from the neutral pool were further purified by reverse-phase high pressure liquid chromatography on a C-18 Bondapak with a linear gradient of acetonitrile (10-60%). The active single peak which eluted at 55% acetonitrile gave a single band when analyzed by polyacrylamide gel electrophoresis. This material stimulated [3H]thymidine incorporation into human fibroblast DNA with approximately 3.2 times the potency of pure Sm-C but was equipotent in stimulating BALB/c 3T3 fibroblasts. It was degraded by fibroblast cultures at a slower rate compared to Sm-C, although it had a similar affinity for Sm-C-binding protein. We conclude that human fibroblasts produce two peptides that react with anti-Sm-C antibody but are chemically distinct from Sm-C. The greater response to fibroblast somatomedin may be due to its affinity for somatomedin-binding protein and slower degradation. These findings may have implications for understanding the regulation of human fibroblast replication.     

Mechanisms of insulin degradation by isolated rat adipocytes

Summary We have examined some of the chemical and biological characteristics of the insulin-derived cell-associated radioactivity following incubation of isolated adipocytes with ¹²⁵I-insulin (10^–10 M) for one hour at 37 °C S ephadex G-50 chromatography of the cell-associated radioactivity demonstrated three peaks: peak I eluted with the void volume and consisted of large molecular weight material; peak II comigrated with 1251-insulin; and peak III consisted of small molecular weight degradation products (probably iodotyrosine). When the insulin peak (peak II) was divided into fourths, it was found that the binding and biologic activity of this material was not homogenous; thus, binding and biologic activity (relative to native insulin) fell markedly from the earliest to the latest eluting fractions of this peak. Furthermore, when the entire peak 11 material was applied to DEAE-Sephacel and eluted with a 0.01–0.2 M NaCl gradient, three distinct peaks were observed. These peaks were all 90% TCA precipitable, whereas the ability of the latter two eluting peaks to precipitate with anti-insulin antiserum was markedly reduced. When similar experiments were performed with chloroquine-treated cells, a large increase in cell-associated radioactivity was observed, and Sephadex G-50 chromatography demonstrated that this increase was entirely confined to peaks I and II. When the insulin peak (peak II) was divided into fourths, it was found that chloroquine markedly inhibited the decreased binding and biologic activity, from the earliest to the latest eluting fraction of this peak. Furthermore, when the peak II material (Sephadex G-50) from chloroquine-treated cells was chromatographed on DEAE-Sephacel, this material eluted in a single peak which was 95% TCA precipitable and 106% precipitable by anti-insulin antiserum. In conclusion, these studies demonstrate that: 1) intermediate insulin-derived products with reduced binding and biologic activity are generated in the process of cellular insulin degradation, and 2) the formation of these intermediate products is mediated by a chloroquine-sensitive pathway.     

IUB commission of editors of biochemical journals the citation of bibliographic references in biochemical journals recommendations (1971)

A pentose-rich acidic glycoprotein was isolated from protease digested bovine vitreous humor by fractionation on an AG1-X2 column using NaCl solution gradient.The material eluted at 0.35 M NaCl (glycoprotein) was electrophoretically heterogeneous at pH 8.6 after partial purification on Sephadex G-25. Gel filtration on G-100 resolved the glycoprotein into two fractions. These fractions differ in molecular weight; mol. wt approx. 95 000 material consisted of two components on electrophoresis and mol. wt approx. 28 000 material showed only a single component on electrophoresis. The lower molecular weight component was re-chromatographed on Sephadex G-100 yielding a single orcinol positive component which gave a homogeneous band on gel electrophoresis.Quantitative analysis of this material gave 30% protein, 7.0% pentose, 18.7% glucosamine, 9.2% galactosamine, 10.9% hexuronic acid and 16.1% hexose.Treatment with 0.5 M NaOH at 20°C for 24 h resulted in a 50% decrease in the threonine content suggesting the possible involvement of this amino acid in the protein-carbohydrate linkage group.Paper chromatography of the fraction hydrolysate demonstrated the presence of glucurone, xylose, arabinose, glucose and galactose.     

[Identification and characterization of two phospholipase A2 activities in resident mouse peritoneal macrophages.]

The interaction between bovine antithrombin, a plasma proteinase inhibitor, and heparin species of different molecular weights was studied. A commercial heparin preparation was divided by gel chromatography into a number of fractions with average molecular weights ranging from 6000 to 34700. Each of these fractions was further fractionated by affinity chromatography on matrix-bound antithrombin. In the latter procedure, those heparin fractions that had molecular weights lower than about 14000 were separated into three peaks. The material in the first of these was not adsorbed on the column, and the other two peaks corresponded to the low-affinity and high-affinity peaks described previously. In contrast, high-molecular-weight heparin samples gave only the low-affinity and high-affinity fractions. U.v. difference absorption studies showed that the non-adsorbed heparin fraction bound to antithrombin in solution with a binding constant at physiological ionic strength only slightly lower than that of low-affinity heparin. The division between the two fractions thus is arbitrary and only dependent on the conditions selected for the affinity-chromatography experiment. Stoicheiometries and binding constants for the binding of several high-affinity heparin species to antithrombin were determined by fluorescence titrations. High-affinity heparin fractions of equal elution positions in the beginning of the peaks of the affinity chromatographies, but with different molecular weights, showed stoicheiometries that were not experimentally distinguishable from 1:1 and also had no appreciable differences in binding constants. However, the anticoagulant activities, calculated on a molar basis, of these fractions increased markedly with molecular weight, a behaviour that thus cannot be explained by differences in the binding of the fractions to antithrombin. In contrast, high-affinity samples of similar molecular weights, which were eluted at increasing ionic strengths from matrix-linked antithrombin, were found to have an increasing proportion of chains with two binding sites for antithrombin and also to have progressively higher binding constants. These binding properties at least partly explain the increasing anticoagulant activities that were observed for these fractions.     

Identification and Characterization of Two DNA Polymerase Activities Present in Trypanosoma brucei Mitochondria

We have identified and partially purified two DNA polymerase activities from purified Trypanosoma brucei mitochondrial extracts. The DNA polymerase activity eluted from the single-stranded DNA agarose column at 0.15 M KCI (polymerase MI) was significantly inhibited by salt concentrations greater than 100 mM, utilized Mg²⁺ in preference to Mn²⁺ as a cofactor on deoxyribonucleotide templates with deoxyribose primers, and in the presence of Mn²⁺ favored a ribonucleotide template with a deoxyribose primer. A 44 kDa peptide in this fraction crossreacted with antisera against the Crithidia fasciculata β-like mitochondrial polymerase. In activity gels the catalytic peptide migrated at an apparent molecular weight of 35 kDa. The DNA polymerase activity present in the 0.3 M KCI DNA agarose fraction (polymerase M2) exhibited optimum activity at 120-180 mM KCI, used both Mg²⁺ and Mn²⁺ as cofactors, and used deoxyribonucleotide templates primed with either deoxyribose or ribose oligomers. Activity gel assays indicate that the native catalytic peptide(s) is ˜ 80 kDa in size. The two polymerases showed different sensitivities to several inhibitors: polymerase MI shows similarities to the Crithidia fasciculata β-like mitochondrial polymerase while polymerase M2 is a novel, salt-activated enzyme of higher molecular weight.     

Preparation of target antigens specifically recognized by human natural killer cells

In an attempt to identify target cell membrane molecules recognized by natural killer (NK) cells, artificial membranes were prepared from detergent-solubilized plasma membranes of NK target cells and synthetic lipids. Such reconstituted membranes from human and rat NK target cells were shown to inhibit both human and rat NK-target cell conjugates in a species-specific fashion; these reconstituted membranes failed to inhibit NK cytotoxicity. The detergent-solubilized material from the human NK target K562 was subjected to various procedures prior to reconstitution and the conjugate inhibition assay. Conjugate inhibitory activity was lost upon trypsin digestion and incubation at 65 degrees C. This inhibition activity was absorbed to concanavalin A agarose and could subsequently be eluted with alpha-methylmannoside, resulting in approximately 20-fold purification. Gel filtration of this material on an AcA-34 column in detergent gave a broad activity peak with maximal activity in the molecular weight range of 30,000-165,000. Gel electrophoresis of purified membranes demonstrated multiple molecular weight bands in lipid membranes. The K562 membrane material, purified by concanavalin A agarose and gel filtration, inhibited conjugates between human NK cells and any of four human target cells, but not of conjugates with (1) human large granular lymphocytes and antibody-coated mouse tumor cells nor (2) rat NK cells and their target cells. Thus the purified glycoproteins from K562 retain the property of specific inhibition of human NK-target conjugates.     

Isolierung und Charakterisierung schnell markierter RNS von Euglena gracilis mit Hilfe analytischer und präparativer Elektrophorese in Polyacrylamid-Gelen

Zusammenfassung MAK-Säulenchromatographie der Gesamtnucleinsäuren aus autotrophen und gebleichten Zellen von Euglena gracilis, welche für 2 Std mit ³²P-Orthophosphat markiert wurden, liefert 6 Komponenten: niedermolekulare RNS (I–III), DNS (IV) und hochmolekulare RNS (V, VI). Das in der DNS-Region eluierte Material konnte mittels Gelfiltration in ³²P-DNS, in eine ³²P-RNS mit hoher spezifischer Aktivität sowie in ³²P-markierte Polyphosphate aufgetrennt werde. Außerdem fanden sich letztere in der ³²P-RNS-Fraktion, die relativ fest an die MAK-Säule gebunden bleibt. Eine weitaus bessere Auftrennung der einzelnen RNS-Komponenten gelang mit der Elektrophorese in Polyacrylamid-Gelen. So erschienen in 9.5% Gel 5 Komponenten, darunter die 3 niedermolekularen I–III, welche bei MAK-Chromatographie auftreten. Sie wurden als 4 S Transfer-RNS (I), 5 S ribosomale RNS (II) und 6 S RNS (III) identifiziert. Die hochmolekulare RNS wurde bei Auftrennung in 2,6% Gel in 6 Banden zerlegt. Die der ribosomalen RNS fanden sich als Hauptbanden in der 24 S und 20 S Region des Gels. Aufgrund ihrer Position konnten für die übrigen Komponenten Sedimentationskoeffizienten zwischen 18 S und 9 S berechnet werden. Das elektrophoretische Trennmuster der Gesamtnucleinsäuren aus gebleichten Zellen war sehr ähnlich, wenngleich quantitative Unterschiede zwischen den einzelnen Komponenten bestanden. Bei der Fraktionierung der Nucleinsäuren durch Gel-Elektrophorese im präparativen Maßstab fiel für jede markierte RNS-Komponente genügend Material an, um eine Rechromatographie an MAK und die Bestimmung der Basenzusammensetzung durchzuführen. Außer Transfer-RNS und 5 S RNS wurden 2 Komponenten in 9,5% Gel isoliert, deren Zusammensetzung ribosomaler RNS entsprach. Eine weitere niedermolekulare Komponente wurde als die schnell markierte RNS identifiziert, welche gemeinsam mit der DNS von der MAK-Säule eluiert wird. Die präparative Gel-Elektrophorese der ³²P-markierten hochmolekularen RNS in 2,6% Gel lieferte neben mehreren ribosomalen Species auch ³²P-RNS mit einer hohen spezifischen Aktivität.

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Isolation and characterization of rapidly labelled RNA from Euglena gracilis by means

Summary MAK column chromatography of total nucleic acids from autotrophic and bleached cells of Euglena gracilis cultured with ³²P_i for 2 h resulted in the separation of six labelled components: low molecular RNA (I–III), DNA (IV) and high molecular RNA (V, VI). Gel filtration of the material eluted in the DNA region revealed the presence of ³²P-RNA with a high specific activity and of ³²P-labelled polyphosphates in addition to ³²P-DNA. ³²P-polyphosphates were also found among the labelled RNA tenaciously bound to the MAK column. A far better resolution of the RNA components, however, was achieved by polyacrylamide-gel electrophoresis. On a 9.5% gel five main fractions were resolved among which appeared the components I–III isolated by MAK chromatography. They were identified as 4 S transfer RNA (I), 5 S ribosomal RNA (II) and 6 S RNA (III). The high molecular RNA gave rise to six bands when a 2.6% gel was used. From these the ribosomal RNA migrated as two bands in the 24 S and 20 S region of the gel. Based upon these values sedimentation coefficients from 18 S to 9 S were calculated for the others. The electrophoretic pattern of total nucleic acids from bleached cells was rather similar; only quantitative differences were observed. Fractionation of the nucleic acids by polyacrylamide-gel electrophoresis on a preparative scale provided enough material of each labelled RNA component to perform a rechromatography on MAK and to determine the base composition. Besides the 4 S transfer RNA and the 5 S RNA two RNA components with a ribosomal type base composition were isolated on a 9.5% gel. Another one was identified as the rapidly labelled RNA which is eluted with the DNA from the MAK column. Preparative gel electrophoresis of the labelled high molecular RNA (2.6% gel) revealed the presence of several ribosomal species in addition to ³²P-RNA components with a high specific activity.

     

Large Scale Purification of Isoinhibitors of Trypsin from Swine Colostrum Using Zinc Chelate Chromatography and Chromatofocusing

Low molecular weight trypsin inhibitors were purified from swine colostrum on a large scale under mild conditions. Ammonium sulfate fractionation and metal chelate chromatography on zinc chelate Sepharose and phenyl Sepharose were used for removal of the bulk of proteins. The inhibitors showed only a weak hydrophobic interaction with phenyl Sepharose even in the presence of 1 M (Nll₄)₂SO4, and advantage was taken of this property to remove the inhibitors from contaminating colostrum proteins which remained tightly adsorbed to phenyl Sepharose under these conditions. The low and high molecular weight inhibitors were then separated by gel filtration on Bio-Gel P-300. The low molecular weight material was eluted in three major inhibitor fractions on DEAE-Sepharose.

Chromatofocusing of these fractions provided greater resolution of the inhibitors, and several previously unreported inhibitor peaks were detected. The six major inhibitors purified by chromatofocusing were homogeneous as judged by polyacrylamide gel electrophoresis in the presence and absence of sodium dodecyl sulfate. These inhibitors were composed of a single polypeptide chain with a molecular weight of 18,000 as determined by Sephacryl S-200 gel filtration and polyacrylamide qel electrophoresis in the presence of sodium dodecyl sulfate and e-mercaptoethanol. The specific activities of the pure inhibitors were approximately 30% higher than those previously reported.     

Drop weight variation in an automated collection procedure and its relationship to apparent surface tension.

A drop counter-regulated fraction collector yields samples containing equal numbers of drops. Such fractions vary slightly in weight depending on experimental conditions such as surface tension. Provided that variables such as flow rate and eluate density remain constant, apparent surface tension may be estimated directly from the weights of eluate fractions obtained from gel filtration experiments. The detergents sodium cholate and sodium lauryl sulphate significantly decreased drop weights in this system. Following gel filtration on Sepharose 4B, sodium cholate eluted in the fractions containing low molecular weight material. It eluted in the same position when pre-mixed with human plasma. Normal plasma was found to contain two surface tension-reducing components with apparent molecular weights of 3-10(6) and 1-10(5). The apparent surface tension of whole human plasma was found to be time dependent and decreased as the flow rate was reduced.     

Interactions between different corneal proteoglycans.

Proteoglycans were extracted from bovine cornea with 4M-guanidinium chloride and purified by CsCl-density-gradient centrifugation. Under associative conditions two fractions were found: one capable of forming assemblies of high molecular weight and another lacking this property. The heavier fraction (density 1.59 g/ml) was eluted as a single retarded peak from Sepharose 2B, but on DEAE-Sephadex chromatography, gave two peaks: the first (eluted with 0.75 M-NaCl) contained mainly proteochondroitin sulphate and the second (eluted with 1.25 M-NaCl) mainly proteokeratan sulphate. Each of these proteoglycans was more retarded on Sepharose 2B than was the original sample from density-gradient centrifugation. Re-aggregation was obtained by recombination of the two fractions. The lighter fraction (density 1.44 g/ml), containing predominantly keratan sulphate chains, was eluted from DEAE-Sephadex as a single peak with 1.25 M-NaCl and was retarded on Sepharose 2B: this fraction was not able to form aggregates with proteochondroitin sulphate. Chemical analyses of the carbohydrate and protein moieties of the proteoglycans from DEAE-Sephadex confirmed that, in the cornea, different subunits are present with characteristic aggregation properties and hydrodynamic volumes.     

Purification of murine thymus leukemia antigen (TL). A quantitative assessment of limited proteolysis.

The murine thymus leukemia antigen (TL) has been solubilized from the tumor ASL1 and from an established cell line ASL1W, by papain digestion. When a 15-min digest was chromatographed on Sephadex G-200, two peaks of TL activity were eluted with apparent molecular weights of approximately 58,000 and 31,000. Chromatography of a 30-min digest under the same conditions resulted in elution of a single peak of activity with an apparent molecular weight of 58,000. Additional purification was carried out on the 58,000 molecular weight material by absorption to, and elution from DEAE-cellulose. The combination of gel filtration and ion exchange chromatography resulted in approximately a 150-fold purification.     

Drop weight variation in an automated collection procedure and its relationship to apparent surface tension

A drop counter-regulated fraction collector yields samples containing equal numbers of drops. Such fractions vary slightly in weight depending on experimental conditions such as surface tension. Provided that variables such as flow rate and eluate density remain constant, apparent surface tension may be estimated directly from the weights of eluate fractions obtained from gel filtration experiments.The detergents sodium cholate and sodium lauryl sulphate significantly decreased drop weights in this system. Following gel filtration on Sepharose 4B, sodium cholate eluted in the fractions containing low molecular weight material. It eluted in the same position when pre-mixed with human plasma.Normal plasma was found to contain two surface tension-reducing components with apparent molecular weight of 3· 10⁶ and 1·10⁵. The apparent surface tension of whole human plasma was found to be time dependent and decreased as the flow rate was reduced.     

Purification and characterization of kallikrein-like serine proteases from rat submandibular glands.

The purification and characterization of kallikrein-like proteases from rat submandibular glands is described. The proteolytic activity of each fraction during purification was monitored on the synthetic substrate N-alpha-tosyl-L-arginine methyl ester (TAME). The purification scheme involved ammonium sulfate precipitation, chromatography on columns of DEAE-Sepharose and Sephadex G-100 and chromatofocusing. Three TAME-hydrolytic activity peaks were eluted from DEAE-Sepharose as unbound fraction (Pool 1), at 125 mM NaCl (Pool 2) and at 250 mM NaCl concentration (Pool 4). Pool 1 further resolved into two protease fractions (1A1 and 1A2), pool 2 into three protease fractions (2A1, 2A2 and 2A3) and pool 4 gave a single major protease peak (4A1) by chromatofocusing on PBE-94. Protease pools 2A2, 2A3, and 4A1 each gave a single band on SDS-polyacrylamide gel electrophoresis with an estimated molecular weight of 34 kDa, 46 kDa and 46 kDa respectively. Pools 1A1, 1A2, 2A1 and 2a2 gave a single precipitin line with anti-rat glandular kallikrein antibodies. 2A3 and 4A1 did not react with these antibodies. Synthetic substrates DL-val-leu-arg-pNA and Bz-pro-phe-arg-pNA, specific for kallikrein-like proteases, were hydrolyzed preferentially by 2A3 and 4A1 but were poor substrates for 1A1, 1A2, 2A1 and 2A2.     

SELECTIVE RETENTION AND FILTRATION OF BRAIN NUCLEIC ACIDS IN AGAROSE GELS

Abstract— Total nucleic acids of rat brain have been separated by agarose gel chromatography at 2 m -NaCl into DNA. transfer RNA plus low molecular weight RNA. and high molecular weight RNA fractions. The DNA fraction contained less than 1 per cent RNA by weight judged by either short-term or long-term labelling with ortho[³²P]phosphate. The high molecular weight RNA fraction contained 28 s and 18 s ribosomal RNAs and a heterogeneous population of 20-60 s RNAs, apparent after short-term labelling and characterized by a high content of nearest-neighbour-labelled uridylic acid. The rapidly sedimenting (>30 s ) portion of these RNAs could be largely separated from ribosomal RNAs by gel filtration using 4% agarose. The ribosomal RNAs could be fully resolved into 28 s and 18 s components by agarose gel chromatography at 0.5 m -0.6 m -NaCl, as shown by analysis of their sedimentation and nucleotide composition.     

Transformation in pneumococcus: protein content of eclipse complex.

A two-step purification of pneumococcal eclipse complex is described, which uses sucrose gradient sedimentation followed by agarose gel permeation chromatography. Purified complex contains, in addition to donor DNA single strands, macromolecular material that can be labeled with methionine or leucine during development of competence. This material co-chromatographed with eclipse complex DNA on hydroxylapatite, was dissociated from the DNA by sodium dodecyl sulfate, and was completely digested by Pronase. The sodium dodecyl sulfate-released material eluted as a single peak in sodium dodecyl sulfate chromatography. These properties were consistent with the noncovalent association with eclipse complex of a protein or class of proteins with a narrow range of polypeptide sizes. Evidence for the specific association of this protein with transforming DNA is eclipse was also obtained from parallel purification from 35S-labeled nontransformed cells; the amount of methionine label in the corresponding fractions in such cells was only 5% of that in transformed cells.     

Effects of Rheological Properties and Molecular Weight Distribution on the Spinnability of Soy Protein

Experiments were carried out to elucidate the correlation between gel chromatographic profiles and rheological properties of dope with respect to the spinnability of soy protein. It was found that dope prepared with 20% protein concentrate and 1.2% sodium hydroxide showed a good transition zone from rubber-like elasticity to rubber-like flow, as frequency (log ω) in limitation was increased from ?1 to 1, and also the dope showed good spinnability when prepared in the above manner. Good spinnable dopes showed three main fractions in the gel chromatographic profiles on using a Sepharose 4B gel column. The first peak was of a high molecular weight fraction (M_w > 1,000,000) eluted at the void volume, the second peak was of low molecular weight fraction (M_w < 200,000; the peak was around 10,000) eluted at the end of the gel chromatogram, and the third part was a gentle upward slope between the two peaks (1,000,000 > M_w > 200,000). It was clear that the spinnabilities and rheological properties of dope depended on differences in composition of the three main fractions mentioned.     

Partial purification of a high molecular weight hepatocyte growth stimulating factor from normal calf serum.

A heparin-binding protein, acting as a potent hepatocyte growth stimulating factor (HGSF) was extracted and partially purified from normal calf serum. HGSF stimulated DNA synthesis and proliferation in primary cultures of adult Balb/c mouse hepatocytes and in two liver-derived epithelial cell lines (C6 and C2.8) plated at low cell density in serum-free medium in the absence of epidermal growth factor. HGSF was non-dialyzable in M(r) 50,000 cutoff membranes, and was purified after chromatofocusing on PBE94 resin, (NH4)2SO4 precipitation (80% salt concentration) of the active fractions eluted at pH 5.7, flow chromatography and elution through Sephacryl S300 HR and HA-Ultrogel columns. The hepatotrophic activity was eluted with a protein fraction that was concentrated approximately 40,000 fold over the starting material. The effect was half maximal at approximately 50 ng/ml on adult hepatocytes in primary culture, HGSF had a molecular weight of 90,000-110,000 by gel filtration, was unstable on heat-treatment and was completely inhibited after trypsin digestion and after reduction with dithiothreitol. HGSF did not stimulate growth in Balb/c 3T3 fibroblasts. When injected into partially (40%) hepatectomized Balb/c mice, HGSF increased hepatic DNA synthesis 2 to 4-fold over the background stimulation, at 20 hours after the hepatectomy.     

Separation of human leukocyte interferon components by concanavalin A-agarose affinity chromatography and their characterization.

Human leukocyte interferon (HL-IF), produced by mixed leukocytes infected with Newcastle disease virus, was resolved into three distinct fractions when chromatographed on concanavalin A-agarose. The major portion (70--75%) of interferon appeared in the breakthrough (BT fraction). The bound interferon (25--30%) was displaced from the column as two peaks: the first was eluted with 0.01 M methyl alpha-D-mannoside, yielding 15-20% of the interferon activity (alpha-MM fraction), and the second by including ethylene glycol (70%) in the eluant, yielding the remaining 5--15% of the interferon (EG fraction). No interferon was retained when HL-IF produced in the presence of glycosylation inhibitors (tunicamycin or 2-deoxy-D-glucose) was chromatographed on concanavalin A-agarose, suggesting that the fraction of interferon retained by this lectin is glycosylated. The three fractions of interferon (BT, alpha-MM, and EG) were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, cross-species antiviral activity, and neutralization by specific antisera. The BT fraction contains exclusively the 16 000 molecular weight component of human leukocyte interferon. The majority of the alpha-MM fraction (90%) is the 21 000 molecular weight component. However, the EG fraction contains the 16 000 and 21 000--23 000 molecular weight components in essentially equal proportions. On the basis of cross-species antiviral activity and neutralization by specific antisera, the BT and alpha-MM fractions are leukocyte-type interferon and the EG fraction seems to be primarily of fibroblast type.