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Callaerts N, Hocquet A, Wieber F. "Conducted Properly, Published Incorrectly": The Evolving Status of Gel Electrophoresis Images Along Instrumental Transformations in Times of Reproducibility Crisis. BERICHTE ZUR WISSENSCHAFTSGESCHICHTE 2023; 46:233-258. [PMID: 37431677 DOI: 10.1002/bewi.202200051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
For the last ten years, within molecular life sciences, the reproducibility crisis discourse has been embodied as a crisis of trust in scientific images. Beyond the contentious perception of "questionable research practices" associated with a digital turn in the production of images, this paper highlights the transformations of gel electrophoresis as a family of experimental techniques. Our aim is to analyze the evolving epistemic status of generated images and its connection with a crisis of trust in images within that field. From the 1980s to the 2000s, we identify two key innovations (precast gels and gel docs) leading to a "two-tiered" gel electrophoresis with different standardization procedures, different epistemic statuses of the produced images and different ways of generating (dis)trust in images. The first tier, exemplified by differential gel electrophoresis (DIGE), is characterized by specialized devices processing images as quantitative data. The second tier, exemplified by polyacrylamide gel electrophoresis (PAGE), is described as a routine technique making use of image as qualitative "virtual witnessing." The difference between these two tiers is particularly apparent in the ways images are processed, even though both tiers involve image digitization. Our account thus highlights different views on reproducibility within the two tiers. Comparability of images is insisted upon in the first tier while traceability is expected in the second tier. It is striking that these differences occur not only within the same scientific field, but even within the same family of experimental techniques. In the second tier, digitization entails distrust, whereas it implies a collective sentiment of trust in the first tier.
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Affiliation(s)
| | - Alexandre Hocquet
- AHP - PReST, Université de Lorraine & CNRS, Nancy, France
- KHK cultures of research, RWTH, Aachen, Germany
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Ibrahim HR, Tatsumoto S, Ono H, Van Immerseel F, Raspoet R, Miyata T. A novel antibiotic-delivery system by using ovotransferrin as targeting molecule. Eur J Pharm Sci 2014; 66:59-69. [PMID: 25315410 DOI: 10.1016/j.ejps.2014.10.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 09/04/2014] [Accepted: 10/02/2014] [Indexed: 01/09/2023]
Abstract
Synthetic antibiotics and antimicrobial agents, such as sulfonamide and triclosan (TCS), have provided new avenues in the treatment of bacterial infections, as they target lethal intracellular pathways. Sulfonamide antibiotics block synthesis of folic acid by inhibiting dihydrofolate reductase (DHFR) while TCS block fatty acid synthesis through inhibition of enoyl-ACP reductase (FabI). They are water-insoluble agents and high doses are toxic, limiting their therapeutic efficiency. In this study, an antibiotic drug-targeting strategy based on utilizing ovotransferrin (OTf) as a carrier to allow specific targeting of the drug to microbial or mammalian cells via the transferrin receptor (TfR) is explored, with potential to alleviate insolubility and toxicity problems. Complexation, through non-covalent interaction, with OTf turned sulfa antibiotics or TCS into completely soluble in aqueous solution. OTf complexes showed superior bactericidal activity against several bacterial strains compared to the activity of free agents. Strikingly, a multi-drug resistant Salmonella strain become susceptible to antibiotics-OTf complexes while a tolC-knockout mutant strain become susceptible to OTf and more sensitive to the complexes. The antibiotic bound to OTf was, thus exported through the multi-drug efflux pump TolC in Salmonella wild-type strain. Further, antibiotics-OTf complexes were able to efficiently kill intracellular pathogens after infecting human colon carcinoma cells (HCT-116). The results demonstrate, for the first time, that the TfR mediated endocytosis of OTf can be utilized to specifically target drugs directly to pathogens or intracellularly infected cells and highlights the potency of the antibiotic-OTf complex for the treatment of infectious diseases.
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Affiliation(s)
- Hisham R Ibrahim
- Department of Biochemistry and Biotechnology, Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan.
| | - Sayuri Tatsumoto
- Department of Biochemistry and Biotechnology, Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan
| | - Hajime Ono
- Department of Biochemistry and Biotechnology, Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan
| | - Filip Van Immerseel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke 9820, Belgium
| | - Ruth Raspoet
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke 9820, Belgium
| | - Takeshi Miyata
- Department of Biochemistry and Biotechnology, Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan
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Chrambach A, Pickett J, Schlam ML, Kapadia G, Holtzman NA. A Partitioned Slab Apparatus for One-Dimensional Polyacrylamide Gel Electrophoresis in Multiphasic Buffer Systems under a Wide Range of Conditions. ACTA ACUST UNITED AC 2006. [DOI: 10.1080/00372367208057981] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- A. Chrambach
- a REPRODUCTION RESEARCH BRANCH , NATIONAL INSTITUTE FOR CHILD HEALTH AND HUMAN DEVELOPMENT NATIONAL INSTITUTES OF HEALTH , BETHESDA , MARYLAND , 20014
| | - J. Pickett
- a REPRODUCTION RESEARCH BRANCH , NATIONAL INSTITUTE FOR CHILD HEALTH AND HUMAN DEVELOPMENT NATIONAL INSTITUTES OF HEALTH , BETHESDA , MARYLAND , 20014
| | - M. L. Schlam
- a REPRODUCTION RESEARCH BRANCH , NATIONAL INSTITUTE FOR CHILD HEALTH AND HUMAN DEVELOPMENT NATIONAL INSTITUTES OF HEALTH , BETHESDA , MARYLAND , 20014
| | - G. Kapadia
- a REPRODUCTION RESEARCH BRANCH , NATIONAL INSTITUTE FOR CHILD HEALTH AND HUMAN DEVELOPMENT NATIONAL INSTITUTES OF HEALTH , BETHESDA , MARYLAND , 20014
| | - N. A. Holtzman
- b DEPARTMENT OF PEDIATRICS , THE JOHNS HOPKINS UNIVERSITY SCHOOL OF MEDICINE , BALTIMORE , MARYLAND , 21205
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NAKAMURA RYO, MATSUDA TSUKASA. A New Protein Band Appearing in the Electrophoretic Pattern of Egg White Heated at Below 60°C. J Food Sci 2006. [DOI: 10.1111/j.1365-2621.1983.tb14795.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Legowo AM, Imade T, Hayakawa S. Heat-induced gelation of the mixtures of α-lactalbumin and β-lactoglobulin in the presence of glutathione. Food Res Int 1993. [DOI: 10.1016/0963-9969(93)90064-p] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kühle K, Kleinow W. Glycosidases in Brachionus plicatilis (Rotifera). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1990; 95:393-402. [PMID: 2328573 DOI: 10.1016/0305-0491(90)90093-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1. Tests for glycosidases were performed in homogenates of Brachionus plicatilis. 2. Hydrolytic activity was detected with the following substrates: (a) with synthetic substrates (NP = 4-nitrophenyl): NP-alpha- and NP-beta-D-glucopyranoside, NP-alpha- and NP-beta-D-galactopyranoside, NP-N-acetyl-beta-D-glucosaminide, NP-N-acetyl-beta-D-galactosaminide, NP-alpha- and NP-beta-D-mannopyranoside and NP-alpha-L-fucopyranoside; (b) with disaccharides: sucrose, maltose, trehalose, isomaltose, cellobiose, gentiobiose and lactose; (c) with polysaccharides: laminarine, carboxymethyl-cellulose, avicel, Micrococcus luteus (for lysozyme) and 4-nitrophenyl-alpha-D-maltoheptaoside (for amylase). 3. The pH dependence of the glycosidase activities was determined. 4. The distribution of enzyme activities within fractions from the homogenate was studied in order to localize them within the cell. 5. Proteins from Brachionus homogenate were separated by SDS-gel electrophoresis and the positions of the following glycosidase activities were detected by assays performed on the gels (estimated molecular weights in parentheses): alpha-glucosidase (250,000); beta-glucosidase (200,000); beta-galactosidase (70,000); N-acetyl-beta-glucosaminidase (60,000).
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Affiliation(s)
- K Kühle
- Zoologisches Institut der Universität zu Köln, West Germany
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Mizote T, Nakayama H. Purification and properties of hydroxymethylpyrimidine kinase from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 991:109-13. [PMID: 2540841 DOI: 10.1016/0304-4165(89)90035-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hydroxymethylpyrimidine kinase, which catalyzes the conversion of 2-methyl-4-amino-5-hydroxymethylpyrimidine (hydroxymethylpyrimidine) to its monophosphate, is purified about 3300-fold to apparent homogeneity from the cell-free extracts of E. coli K-12 through four successive steps of column chromatographies. The purified enzyme gave a single protein band on polyacrylamide gel electrophoresis and its molecular weight is estimated to be 43 000-44 000. The enzyme phosphorylated each of the pyridoxine substrates, pyridoxine, pyridoxal and pyridoxamine as well as hydroxymethylpyrimidine, and the reaction gave rise to a corresponding 5'-phosphate compound. The Km values of the purified enzyme for hydroxymethylpyrimidine and for pyridoxine are 1.1.10(-4) and 6.6.10(-5) M, respectively. Pyridoxine inhibits competitively the phosphorylation of hydroxymethylpyrimidine with a Ki value of 2.7.10(-6) M and hydroxymethylpyrimidine shows the same for that of pyridoxine with a Ki value of 9.0.10(-5) M. A similarity in enzymic properties between the hydroxymethylpyrimidine kinase and an enzyme which has been characterized as pyridoxal kinase leads to the assumption that both hydroxymethylpyrimidine and pyridoxine might be phosphorylated by the same enzyme species.
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Affiliation(s)
- T Mizote
- Department of Food and Nutrition, Yamaguchi Women's University, Japan
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DANNA KATHLEENJ, SACK GEORGEH, NATHANS DANIEL. Studies of Simian Virus 40 DNA VII. A Cleavage Map of the SV40 Genome. Mol Biol 1989. [DOI: 10.1016/b978-0-12-131200-8.50036-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Oikawa T, Sendai Y, Kurata S, Yanagimachi R. A glycoprotein of oviductal origin alters biochemical properties of the zona pellucida of hamster egg. GAMETE RESEARCH 1988; 19:113-22. [PMID: 3209175 DOI: 10.1002/mrd.1120190202] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Eggs were isolated from ovaries and oviducts of the golden hamster and the components of zonae pellucidae were examined using density gradient SDS-polyacrylamide electrophoresis. Zonae of ovarian eggs (ZP-OVA) had three major components corresponding to the so-called ZP-1, ZP-2, and ZP-3. Zonae of recently ovulated eggs collected from oviducts (ZP-OVI) had a 200-240 K component (ZP-O) in addition to the three components present in ZP-OVA. When ovarian and oviductal eggs were stained with FITC-conjugated B. simplicifolia-1 lectin (BS-1), which specifically binds to alpha-D-galactose- or alpha-N-acetyl-D-galactosamine-like terminal saccharide residues, ZP-OVI was intensely stained, while ZP-OVA was not. ZP-OVA gained the ability to bind to BS-1 after a brief treatment with oviduct extracts. These results suggest that biochemical properties of hamster zonae change after transport of eggs from ovary to the oviduct. The addition of the 200-240 K component of oviductal origin to preexisting zona components seems to be responsible for this change.
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Affiliation(s)
- T Oikawa
- Bio Science Laboratory and Developmental and Reproductive Biology Center, Yamagata, Japan
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12
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Chemical properties of the lorica and related parts from the integument of Brachionus plicatilis. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/0305-0491(88)90163-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Worrall EB, Gassain S, Cox DJ, Sugden MC, Palmer TN. 3-Hydroxyisobutyrate dehydrogenase, an impurity in commercial 3-hydroxybutyrate dehydrogenase. Biochem J 1987; 241:297-300. [PMID: 3494445 PMCID: PMC1147556 DOI: 10.1042/bj2410297] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The enzymic determination of D-3-hydroxybutyrate and acetoacetate normally involves the use of 3-hydroxybutyrate dehydrogenase (HBDH, EC 1.1.1.30) of bacterial origin. We show that HBDH from Rhodopseudomonas spheroides (BCL, grade II) contains a 3-hydroxyisobutyrate dehydrogenase (HIBDH) activity: activity with 3-hydroxyisobutyrate as substrate was greater than 10% of that with 3-hydroxybutyrate. However, HBDH could be prepared essentially free of HIBDH activity by incubation at 37 degrees C in the presence of 1 mM-CaCl2, to produce an enzyme preparation that may be used for the specific determination of 3-hydroxybutyrate. Use of the purified enzyme preparations indicated that a major product of valine metabolism in hemidiaphragms from 40 h-starved rats was 3-hydroxyisobutyrate rather than 3-hydroxybutyrate.
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McLaren RD, McIntosh JT, Howe GW. The purification and characterization of bovine salivary proteins by electrophoretic procedures. Electrophoresis 1987. [DOI: 10.1002/elps.1150080705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Woodfield DG, Simpson LA, Seber GA, McInerney PJ. Blood groups and other genetic markers in New Zealand Europeans and Maoris. Ann Hum Biol 1987; 14:29-37. [PMID: 3592610 DOI: 10.1080/03014468700008811] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Genetic data on the frequency of various red-cell antigens and enzymes as well as polymorphic protein markers from New Zealand European and Maori populations are outlined. Despite widespread intermarriage between races in New Zealand there was, in nearly all systems tested, a significant difference in the frequency of genetic markers.
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Robertson DM, de Vos FL, Foulds LM, McLachlan RI, Burger HG, Morgan FJ, Hearn MT, de Kretser DM. Isolation of a 31 kDa form of inhibin from bovine follicular fluid. Mol Cell Endocrinol 1986; 44:271-7. [PMID: 3082696 DOI: 10.1016/0303-7207(86)90133-4] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The introduction of a pH 4.75 precipitation step to a previously described purification procedure from bovine follicular fluid (bFF) resulted in the isolation of a 31 kDa form of inhibin, in addition to 58 kDa inhibin. The procedure was monitored by an in vitro bioassay based on the suppression of the FSH cell content by pituitary cells in culture. The 31 kDa form was purified 5550-fold with approximately 5% recovery. On SDS-polyacrylamide gel electrophoresis a single band was detected with a molecular weight of 31 000 +/- 1500 (mean +/- SD) which upon reduction gave 2 subunits of 20 200 +/- 300 and 14 800 +/- 600. The biological activity expressed on mg protein basis was similar for both 31 kDa and 58 kDa inhibin although on a molar basis the 58 kDa inhibin was 2-3 times higher. A high degree of cross-reaction was observed between both forms in a radioimmunoassay of bovine inhibin using an antiserum raised against the larger form with either iodinated 31 kDa or 58 kDa inhibin as tracer. Based on the subunit composition of the 31 kDa and 58 kDa inhibin, their similar cross-reaction in a radioimmunoassay system and the apparent generation of the 31 kDa inhibin following a pH precipitation step, it is concluded that 31 kDa inhibin is a smaller form of the 58 kDa inhibin resulting from a shortening of the 43 kDa subunit to a 20 kDa subunit.(ABSTRACT TRUNCATED AT 250 WORDS)
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FUKE YOKO, SEKIGUCHI MASAKATSU, MATSUOKA HIROATSU. Nature of Stem Bromelain Treatments on the Aggregation and Gelation of Soybean Proteins. J Food Sci 1985. [DOI: 10.1111/j.1365-2621.1985.tb10462.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Kinetics of oxygen and carbon monoxide binding to liver fluke (Dicrocoelium dendriticum) hemoglobin. An extreme case? J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89531-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Tsuji S, Kato H, Matsuoka Y, Fukushima T. Molecular weight heterogeneity of bovine serum transferrin. Biochem Genet 1984; 22:1145-59. [PMID: 6397195 DOI: 10.1007/bf00499638] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Cattle transferrin (Tf) was purified from serum of variant A and four bands were isolated. The peptide patterns of these bands when cleaved by proteases and by cyanogen bromide (BrCN) were compared, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Variant A displays two groups of molecules--large (L) and small (S)--on SDS-PAGE; the molecular weight of the L bands is 78,400 +/- 1700 and that of the S bands is 72,000 +/- 1700. However, S-band molecules could not be produced artificially by heat treatment of L bands in the presence of SDS and 2-mercaptoethanol. Since deglycosylated Tf also showed molecular weight heterogeneity, the sugar moieties of Tf other than sialic acids were not the cause of the heterogeneity. These results suggest that heterogeneity within a given variant is due to the presence of two kinds of molecule of different molecular weight. The peptide patterns of L and S bands produced by proteases and those produced by BrCN were distinctly different from each other. However, the stepwise degradation patterns of L and S bands resembled each other when treated with both chymotrypsin and BrCN. This suggests that L-band molecules differ from S-band molecules only in the presence of an additional carboxyl-terminal peptide.
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Holzbach RT, Kibe A, Thiel E, Howell JH, Marsh M, Hermann RE. Biliary proteins. Unique inhibitors of cholesterol crystal nucleation in human gallbladder bile. J Clin Invest 1984; 73:35-45. [PMID: 6690482 PMCID: PMC424968 DOI: 10.1172/jci111204] [Citation(s) in RCA: 182] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The onset time for cholesterol crystal nucleation of supersaturated normal human gallbladder biles is consistently prolonged when compared with biles from patients with cholesterol gallstone disease. Investigation of the factor(s) responsible for the suspended supersaturation (metastability) of normal human biles revealed that model bile solutions of cholesterol saturation index (CSI) and molar lipid composition identical to individual gallbladder bile specimens had much shorter crystal nucleation times, i.e., exhibited decreased metastability. Unsaturated normal biles, after supplementation with lecithin, cholesterol, and sodium taurocholate to a 'standard' supersaturated lipid composition, also demonstrated nucleation times three- to 15-fold longer than the comparable standard model bile. Total lipid extracts of normal biles, however, when similarly supplemented, did not differ in nucleation time from the control model solution. Gallbladder biles were fractionated by gel chromatography and the eluted fractions were pooled into two fractions. The fractions eluting in about the first 25% of the included volume when mixed with the supersaturated standard model bile induced a modest increase in nucleation time of approximately 1.5 times the control value. The fractions eluting in the second 25% of the included volume and which contained all of the bile lipids, were concentrated and supplemented with lipids to the standard composition. The nucleation times of these supplements were 3-10 times longer than the control nucleation times. Delipidated bile protein mixtures, purified by discontinuous sucrose gradient centrifugation, were recombined with purified lipids at the standard composition used previously. The nucleation times of these mixtures were significantly prolonged to the same extent as those associated with the second chromatographic fraction. These observations demonstrate that the delayed onset (inhibition) of cholesterol crystal nucleation observed in normal human gallbladder bile is produced by a factor(s) present in the biliary protein fraction.
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Ohsawa K, Ebata N. Silver stain for detecting 10-femtogram quantities of protein after polyacrylamide gel electrophoresis. Anal Biochem 1983; 135:409-15. [PMID: 6660516 DOI: 10.1016/0003-2697(83)90703-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A rapid and highly sensitive silver stain and color stain were developed for visualizing proteins. The procedure is simple and the bands were clear. This silver stain detects 100 pg quantities of proteins. In order to stain quickly, sensitively, and sharply a protein matrix in a gel, the repeated shrinkage and swelling gel was developed with a hyper- and hypotonic solution to remove the sodium dodecyl sulfate (SDS) from SDS-protein complex and to generate influx of staining solution into the gel. We have found that the silver staining method with the repeated exposure to hyper- and hypotonic solution and a narrow well produced 10 fg order of proteins.
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Modification of bovine somatotropin (growth hormone) with plasmin. Protein J 1983. [DOI: 10.1007/bf01025234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Nugent JH, Jones WT, Jordan DJ, Mangan JL. Rates of proteolysis in the rumen of the soluble proteins casein, fraction I (18S) leaf protein, bovine serum albumin and bovine submaxillary mucoprotein. Br J Nutr 1983; 50:357-68. [PMID: 6615765 DOI: 10.1079/bjn19830103] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The rate of proteolysis in the rumen was dependent on the soluble protein used. With a sheep on a hay + concentrate diet the rates (approximately Vmax) for casein, Fraction I leaf protein and bovine serum albumin were 16.5, 3.4 and 0.9 mg protein nitrogen/l per min respectively. Change of diet from hay + concentrate to fresh lucerne (Medicago sativa) increased the proteolytic rates for all three proteins. Bovine submaxillary mucoprotein degraded extremely slowly in the rumen at approximately 0.5-0.6 mg N/l per min and its sialic acid component was degraded at a similar rate to that of the protein chain. Uniformly 14C-labelled Fraction I leaf protein was used to demonstrate that in the presence of a second protein, competition for enzymic sites occurred. In Fraction I and bovine serum albumin mixtures, reduced rates for the individual proteins of the mixture were observed compared with the proteins treated separately. Treatment of bovine serum albumin with dithiothreitol (0.2 g/l) to cleave disulphide bridges increased the rates of proteolysis by as much as 8.5-fold.
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A yellow affinity substance involved in the cellulolytic system ofClostridium thermocellum. Curr Microbiol 1983. [DOI: 10.1007/bf01567580] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Smith DB, Simpson PA. Relationships of barley proteins soluble in sodium dodecyl sulphate to malting quality and varietal identification. J Cereal Sci 1983. [DOI: 10.1016/s0733-5210(83)80020-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Salo WL, Downing SW, Lidinsky WA, Gallagher WH, Spitzer RH, Koch EA. Fractionation of hagfish slime gland secretions: partial characterization of the mucous vesicle fraction. PREPARATIVE BIOCHEMISTRY 1983; 13:103-35. [PMID: 6878177 DOI: 10.1080/00327488308068743] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
This paper deals with the collection, fractionation and partial characterization of the slime gland secretion of the Pacific hagfish (Eptatretus stouti) with emphasis on the mucous fraction. Secretions were collected by electrical stimulation of the glands of anesthetized hagfish and, using three different methods, separated into three fractions: 1) the thread cells, 2) the mucous vesicles of the mucous cells, and 3) the soluble fraction. The methods take advantage of the stabilization of the thread cells and mucous vesicles by ammonium sulfate and sodium citrate.
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Egin-Bühler B, Ebel J. Improved purification and further characterization of acetyl-CoA carboxylase from cultured cells of parsley (Petroselinum hortense). EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 133:335-9. [PMID: 6133748 DOI: 10.1111/j.1432-1033.1983.tb07467.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Acetyl-CoA carboxylase from irradiated cell-suspension cultures of parsley (Petroselinum hortense) has been purified to apparent homogeneity. The procedure included affinity chromatography of the enzyme on avidinmonomer--Sepharose 4B. Molecular weights of about 420000 for the native enzyme and about 220000 for the enzyme subunit were determined respectively by gel filtration or sucrose-density-gradient sedimentation and by electrophoresis in the presence of dodecyl sulfate. The purified enzyme showed an isoelectric point of 5. The enzyme carboxylated the straight-chain acyl-CoA esters of acetate, propionate, and butyrate at decreasing rates in this order. The catalytic efficiency of the carboxylase was highest when ATP existed largely as MgATP2- complex. At the optimum pH of 8 the apparent Km values for the substrates were: acetyl-CoA, 0.15 mmol/1; bicarbonate, 1 mmol/1; MgATP2-, 0.07 mmol/1. The carboxylase was inhibited by greater than 50 mmol/l NaCl, KCl, or Tris/HCl buffer. The putative allosteric activator, citrate, stimulated the enzyme only slightly at concentrations below 2 mmol/l, but strongly inhibited the carboxylase at higher concentrations. The results of these studies demonstrate that several properties of the light-inducible acetyl-CoA carboxylase of parsley cells, an enzyme of the flavonoid pathway, are remarkably similar to those of acetyl-CoA carboxylases from a variety of other organisms.
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VARUNSATIAN SUNISA, WATANABE KENJI, HAYAKAWA SHIGERU, NAKAMURA RYO. Effects of Ca++, Mg++and Na+on Heat Aggregation of Whey Protein Concentrates. J Food Sci 1983. [DOI: 10.1111/j.1365-2621.1983.tb14785.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kim JS, Gay CV, Schraer R. Purification and properties of carbonic anhydrase from salmon erythrocytes. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1983; 76:523-7. [PMID: 6416738 DOI: 10.1016/0305-0491(83)90286-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Carbonic anhydrase (CA) from erythrocytes of the pink salmon, Onchorhyncus gorbushka, was purified using chloroform-ethanol extraction and Sephadex G-75 gel filtration. A single, high specific-activity CA isozyme having a molecular weight of 29,000 was found. The enzyme sedimented as a single boundary at a sedimentation velocity of 2.9S. Amino acid analysis revealed a composition similar to other submammalian CAs with the exception that the cysteine content was low (1 mol cysteine/mol enzyme). Like other submammalian CAs, the presence of a sulfhydryl reducing agent was required to maintain full activity and to prevent structural changes in the enzyme.
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Abstract
This chapter presents an overview of fatty acid acylation of eukaryotic cell proteins. The chapter describes the distribution of fatty acid acylated proteins, distribution of fatty acid acylated proteins, analysis of the fatty acid, and site and mechanism of fatty acid acylation. Many of the data pertaining to fatty acid acylation of eukaryotic cell membrane proteins come from studies with those glycoproteins that form the external spikes on enveloped RNA animal viruses. The procedures for detecting and identifying protein-bound fatty acids rely primarily on incorporating high specific radioactive labeled fatty acids into growing tissue culture cells and analyzing proteins from these cells by electrophoresis in sodium dodecyl sulfate (SDS)-polyacrylamide gels. The function of fatty acid in membrane proteins is unknown, and it is believed that fatty acid acylation might be important for proper intracellular transport of proteins destined to be localized to the plasma membrane.
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Schousboe I. Characterization of subfractions of beta 2-glycoprotein I: evidence for sialic acid microheterogeneity. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1983; 15:35-44. [PMID: 6825901 DOI: 10.1016/0020-711x(83)90008-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Globin synthesis in hybrid cells constructed by transplantation of dormant avian erythrocyte nuclei into enucleated fibroblasts. Mol Cell Biol 1982. [PMID: 7346715 DOI: 10.1128/mcb.1.12.1163] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The polypeptides synthesized by mature embryonic erythrocytes prepared from the peripheral blood of 14- to 15-day-old chicken embryos were analyzed by two-dimensional gel electrophoresis. Fewer than 200 species of polypeptides were detected; the major polypeptides made at this time were identified as the alpha A-, alpha D-, and beta-globin chains. The dormant erythrocyte nuclei were next reactivated to transcriptional competence by transplantation into enucleated mouse or chicken embryo fibroblasts, with frequencies of cytoplast renucleation of about 50 and 90%, respectively. Since large numbers of hybrid cells could be constructed, a biochemical analysis was possible. Electrophoretic analysis of the [35S]methionine-labeled polypeptides made in the hybrid cell types showed that polypeptides having the mobilities of only two (alpha A and alpha D) of the three major adult globin chains were made as major constituents of the hybrid cells. However, analysis of 14C-amino acid-labeled polypeptides revealed that a beta-like polypeptide that lacked methionine was also synthesized in large amounts. This polypeptide was tentatively identified as the early embryonic globin species rho. Globin synthesis was detected as early as 3 h after nuclear transplantation and as late as 18 h, the last time measured in these experiments. It appeared that globin polypeptides made at very early times were translated at least partially from chicken messenger ribonucleic acid introduced into the hybrid cells during fusion, whereas those made at later times were translated primarily from newly synthesized globin messenger ribonucleic acid. The potential usefulness of this hybrid cell system in analyzing mechanisms regulating globin gene expression is discussed.
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Harrison RA. The interaction of ram proacrosin and acrosin forms with antiserum raised against ram m beta-acrosin. J Reprod Immunol 1982; 4:231-49. [PMID: 6813463 DOI: 10.1016/0165-0378(82)90029-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
An antiserum was raised in rabbits to pure m beta-acrosin, the stable form of active acrosin from ram spermatozoa. By use of immunoprecipitation with Protein A-bearing Staphylococcus aureus cells, so as to react antigen with antibody and isolate the complex rapidly, it could be demonstrated that the anti-m beta-acrosin cross-reacted strongly with native proacrosin, with a degenerate proacrosin form, and with at least one form of active acrosin other than m beta-acrosin. Sperm proteins unrelated to acrosin were not recognized. It is concluded that rabbit anti-m beta-acrosin will react specifically with all the major ram acrosin forms; the antiserum can therefore be used with confidence in immunocytochemical studies to locate both proacrosin and acrosin in ram spermatozoa.
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Legrand-Hamelin E, Souty C, Picaud JL. Le polymorphisme de la lactate déshydrogénase dans des sous-espèces d'Idotea balthica. BIOCHEM SYST ECOL 1982. [DOI: 10.1016/0305-1978(82)90055-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Hille A, Purwin C, Ebel J. Induction of enzymes of phytoalexin synthesis in cultured soybean cells by an elicitor from Phytophthora megasperma f. sp. glycinea. PLANT CELL REPORTS 1982; 1:123-127. [PMID: 24259025 DOI: 10.1007/bf00272369] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/1982] [Indexed: 06/02/2023]
Abstract
The glucan elicitor from cell walls of the fungal pathogen, Phytophthora megasperma f. sp. glycinea, induced rapid but transient increases in enzyme activities of general phenylpropanoid metabolism (phenylalanine ammonia-lyase and 4-coumarate: CoA ligase) and of the flavonoid pathway (chalcone synthase) in cell suspension cultures of soybean (Glycine max). After transferring cells into fresh medium, two peaks of inducibility for the enzymes by elicitor were observed, one shortly after transfer (stage I), and one at the end of the linear growth phase (stage II). Only one of the two isoenzymes of 4-coumarate: CoA ligase ("isoenzyme 2"), for which a specific involvement in flavonoid biosynthesis has been postulated, was affected by the elicitor. For two of the induced enzymes, phenylalanine ammonia-lyase and chalcone synthase, the changes in activity at stage I were shown to be preceded by large changes in their rates of synthesis, as determined by in vivo labelling with [(35)S] methionine and immunoprecipitation.
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Affiliation(s)
- A Hille
- Biologisches Institut II der Universität, Schänzlestr. 1, D-7800, Freiburg, Federal Republic of Germany
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Porumb H, Lascu I, Matinca D, Oarga M, Borza V, Telia M, Popescu O, Jebeleanu G, Bârzu O. Separation of erythrocyte enzymes from hemoglobin by chromatography on Blue-Sepharose. FEBS Lett 1982; 139:41-4. [PMID: 7075764 DOI: 10.1016/0014-5793(82)80482-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Atkinson BG, Atkinson KH. Schistosoma mansoni: one- and two-dimensional electrophoresis of proteins synthesized in vitro by males, females, and juveniles. Exp Parasitol 1982; 53:26-38. [PMID: 7056344 DOI: 10.1016/0014-4894(82)90089-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Sasak W, Herscovics A, Quaroni A. Cell-density-dependent changes in cell-surface glycopeptides and in adhesion of cultured intestinal epithelial cells. Biochem J 1982; 201:359-66. [PMID: 7082294 PMCID: PMC1163651 DOI: 10.1042/bj2010359] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We studied mannose-containing glycopeptides and glycoproteins of subconfluent and confluent intestinal epithelial cells in culture. Cells were labelled with d-[2-(3)H]mannose for 24h and treated with Pronase or trypsin to release cell-surface components. The cell-surface and cell-residue fractions were then exhaustively digested with Pronase and the resulting glycopeptides were fractionated on Bio-Gel P-6, before and after treatment with endo-beta-N-acetylglucosaminidase H to distinguish between high-mannose and complex oligosaccharides. The cell-surface glycopeptides were enriched in complex oligosaccharides as compared with residue glycopeptides, which contained predominantly high-mannose oligosaccharides. Cell-surface glycopeptides of confluent cells contained a much higher proportion of complex oligosaccharides than did glycopeptides from subconfluent cells. The ability of the cells to bind [(3)H]concanavalin A decreased linearly with increasing cell density up to 5 days in culture and then remained constant. When growth of the cells was completely inhibited by either retinoic acid or cortisol, no significant difference was observed in the ratio of complex to high-mannose oligosaccharides in the cell-surface glycopeptides of subconfluent cells. Only minor differences were found in total mannose-labelled glycoproteins between subconfluent and confluent cells by two-dimensional gel analysis. The adhesion of the cells to the substratum was measured at different stages of growth and cell density. Subconfluent cells displayed a relatively weak adhesion, which markedly increased with increased cell density up to 6 days in culture. It is suggested that alterations in the structure of the carbohydrates of the cell-surface glycoproteins are dependent on cell density rather than on cell growth. These changes in the glycopeptides are correlated with the changes in adhesion of the cells to the substratum.
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Baskin DG, Stahl WL. Immunocytochemical localization of Na+, K+-ATPase in the rat kidney. HISTOCHEMISTRY 1982; 73:535-48. [PMID: 6279543 DOI: 10.1007/bf00493367] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
To determine if rat kidney Na+, K+-ATPase can be localized by immunoperoxidase staining after fixation and embedding, we prepared rabbit antiserum to purified lamb kidney medulla Na+, K+-ATPase. When sodium dodecylsulfate polyacrylamide electrophoretic gels of purified lamb kidney Na+, K+-ATPase and rat kidney microsomes were treated with antiserum (1:200), followed by [125I]-Protein A and autoradiography, the rat kidney microsomes showed a prominent radioactive band coincident with the alpha-subunit of the purified lamb kidney enzyme and a fainter radioactive band which corresponded to the beta-subunit. When the Na+, K+-ATPase antiserum was used for immunoperoxidase staining of paraffin and plastic sections of rat kidney fixed with Bouin's, glutaraldehyde, or paraformaldehyde, intense immunoreactive staining was present in the distal convoluted tubules, subcapsular collecting tubules, thick ascending limb of the loops of Henle, and papillary collecting ducts. Proximal convoluted tubules stained faintly, and the thin portions of the loops of Henle, straight descending portions of proximal tubules, and outer medullary collecting ducts did not stain. Staining was confined to basolateral surfaces of tubular epithelial cells. No staining was obtained with preimmune serum or primary antiserum absorbed with purified lamb kidney Na+, K+-ATPase, or with osmium tetroxide postfixation. We conclude that the basolateral membranes of the distal convoluted tubules and ascending thick limb of the loops of Henle are the major sites of immunoreactive Na+, K+-ATPase concentration in the rat kidney.
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Bruno J, Reich N, Lucas JJ. Globin synthesis in hybrid cells constructed by transplantation of dormant avian erythrocyte nuclei into enucleated fibroblasts. Mol Cell Biol 1981; 1:1163-76. [PMID: 7346715 PMCID: PMC369742 DOI: 10.1128/mcb.1.12.1163-1176.1981] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The polypeptides synthesized by mature embryonic erythrocytes prepared from the peripheral blood of 14- to 15-day-old chicken embryos were analyzed by two-dimensional gel electrophoresis. Fewer than 200 species of polypeptides were detected; the major polypeptides made at this time were identified as the alpha A-, alpha D-, and beta-globin chains. The dormant erythrocyte nuclei were next reactivated to transcriptional competence by transplantation into enucleated mouse or chicken embryo fibroblasts, with frequencies of cytoplast renucleation of about 50 and 90%, respectively. Since large numbers of hybrid cells could be constructed, a biochemical analysis was possible. Electrophoretic analysis of the [35S]methionine-labeled polypeptides made in the hybrid cell types showed that polypeptides having the mobilities of only two (alpha A and alpha D) of the three major adult globin chains were made as major constituents of the hybrid cells. However, analysis of 14C-amino acid-labeled polypeptides revealed that a beta-like polypeptide that lacked methionine was also synthesized in large amounts. This polypeptide was tentatively identified as the early embryonic globin species rho. Globin synthesis was detected as early as 3 h after nuclear transplantation and as late as 18 h, the last time measured in these experiments. It appeared that globin polypeptides made at very early times were translated at least partially from chicken messenger ribonucleic acid introduced into the hybrid cells during fusion, whereas those made at later times were translated primarily from newly synthesized globin messenger ribonucleic acid. The potential usefulness of this hybrid cell system in analyzing mechanisms regulating globin gene expression is discussed.
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Driedonks RA, Engel A, tenHeggeler B. Gene 20 product of bacteriophage T4 its purification and structure. J Mol Biol 1981; 152:641-62. [PMID: 7334518 DOI: 10.1016/0022-2836(81)90121-2] [Citation(s) in RCA: 82] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Bernstein RL, Tabler M, Vestweber D, Van Driel R. Extracellular folate deaminase of Dictyostelium discoideum. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 677:295-302. [PMID: 6271253 DOI: 10.1016/0304-4165(81)90099-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Folate deaminase released from cells of Dictyostelium discoideum is heterogeneous with respect to molecular weight and stability at 60 degrees C. The most heat-stable component isoelectrofocuses in a broad band at approx. pH 6. The Km value of this component for folate is approx. 7 x 10(-7)M and Mr approx. 40 000. The major portion if not all of the deaminase binds to immobilized concanavalin A and lentil lectin. Extracellular folate deaminase has a pH-optimum of approx. pH 6.0. This is higher than that of lysosomal enzymes, which are also glycoproteins released into the extracellular medium.
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Buswell JA, Eriksson KE, Pettersson B. Purification and partial characterization of vanillate hydroxylase (decarboxylating) from Sporotrichum pulverulentum. J Chromatogr A 1981. [DOI: 10.1016/s0021-9673(00)81390-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Hirsch HE, Parks ME, Pardridge WM, Casanello-Ertl D. Sarcolemmal protein profiles from cultured myotubes and myoblasts. Exp Neurol 1981; 73:837-41. [PMID: 7262268 DOI: 10.1016/0014-4886(81)90218-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Nugent JH, Mangan JL. Characteristics of the rumen proteolysis of fraction I (18S) leaf protein from lucerne (Medicago sativa L). Br J Nutr 1981; 46:39-58. [PMID: 7260031 DOI: 10.1079/bjn19810007] [Citation(s) in RCA: 90] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
1. The rate of proteolysis of fraction I (18S) leaf protein in the rumen of sheep of cattle was affected by diet ans the rate on fresh lucerne (medicago sativa L) was three to nine times the rate on a hay + concentrate diet. 2. Simultaneous rumen fermentations in vivo and in an artificial rumen showed that the rates of proteolysis of fraction I in vitro was approximately 30% of the rates in sheep. 3. Using 14 C uniformly-labelled fraction I protein at low concentrations, proteolysis exhibited 1st-order kinetics. Over a wide range of protein concentrations the velocity v. substrate concentration curve showed Michaelis-Menten characteristics typical of an enzyme-catalysed reaction. With rumen fluid from a hay + concentrate-fed sheep the maximum velocity was 2.6 mg protein nitrogen/1 per min and the Michaelis constant was 75 mg nitrogen/l. 4. Rapid absorption of 14C-labelled fraction I protein onto bacterial cells preceded proteolysis. 5. Sucrose-density-gradient analysis showed initial incorporation of 14C from protein into rumen bacteria followed by partial transfer to rumen protozoa. 6. No peptides were detected during proteolysis showing that the rate-limiting step occurred during the initial stages of proteolysis. Only small amounts of free amino acids were released except for leucine, isoleucine, valine and ornithine, which showed significantly increased levels. 7. Volatile fatty acids were the main 14C-labelled end products and were rapidly produced in descending concentrations: acetate greater than propionate greater than 3-methyl + 2-methyl butyrate greater than butyrate greater than isobutyrate greater than valerate.
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Helfman D, Shoji M, Kuo J. Purification to homogeneity and general properties of a novel phosphodiesterase hydrolyzing cyclic CMP and cyclic AMP. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69166-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Lascu I, Duc M, Cristea A. Rapid large-scale purification of pig heart nucleoside diphosphate kinase by affinity chromatography on Cibacron Blue 3G-A Sepharose. Anal Biochem 1981; 113:207-11. [PMID: 6269456 DOI: 10.1016/0003-2697(81)90068-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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