scholarly journals Multiple forms of nuclear deoxyribonucleic acid polymerases and their relationship with the soluble enzyme

1973 ◽  
Vol 131 (2) ◽  
pp. 237-246 ◽  
Author(s):  
R. L. P. Adams ◽  
M. A. L. Henderson ◽  
W. Wood ◽  
J. G. Lindsay
Keyword(s):  
Molecular Weight ◽  
Dna Synthesis ◽  
High Molecular Weight ◽  
Dna Polymerase ◽  
Deae Cellulose ◽  
Polymerase Activity ◽  
Enzymic Activity ◽  
Supernatant Fraction ◽  
Molecular Weights ◽  
Molecular Weight Peak

1. DNA polymerase from nuclear and supernatant fractions of cultured mouse L929 cells was fractionated on columns of Sephadex G-200, Sepharose 4B and of DEAE-cellulose. Several peaks of activity are found on Sephadex chromatography and the distribution of activity between these depends on: (a) the source of the enzyme, i.e. nuclear or supernatant fraction; (b) the mode of extraction of the enzyme from the nucleus; (c) the amount of enzyme applied to the column. 2. The DNA polymerase activity in the lower-molecular-weight peaks (approximate molecular weights are 35000, 70000 and 140000) is firmly bound within the cell nucleus and shows a preference for native DNA as template, whereas the high-molecular-weight peak (peak I, molecular weight 250000 or greater) is found in supernatant fractions and shows greater activity with a denatured DNA template. 3. During periods of DNA synthesis the high-molecular-weight enzyme becomes more firmly bound within the nucleus. 4. Peak I enzymic activity is relatively unstable and is inhibited by thiol-blocking reagents and deoxycholate, but it is stimulated by univalent cations. 5. Very little endonuclease is present in the polymerase preparations, but a very active exonuclease and nucleoside diphosphokinase are present. On Sephadex chromatography, however, it was shown that the immediate precursors for DNA synthesis, at least by peak I enzyme, are the deoxyribonucleoside triphosphates. 6. Attempts to decrease the molecular weight of the peak I enzyme while still retaining activity failed.

Is High-Molecular-Weight-Renin Binding of Renin to the Protease Inhibitors and Lipoproteins?

1978 ◽  
Vol 55 (s4) ◽  
pp. 125s-128s
Author(s):  
K. Poulsen ◽  
A. H. Nielsen ◽  
S. Lykkegaard ◽  
C. Malling ◽  
J. Krøll ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Protease Inhibitors ◽  
Plasma Proteins ◽  
Tertiary Structure ◽  
Limited Proteolysis ◽  
Submaxillary Gland ◽  
Enzymic Activity ◽  
Molecular Weights ◽  
Α2 Macroglobulin

1. Two high-molecular-weight forms of renin (molecular weights 800 000 and 70 000) are present in mouse plasma. 2. The 800 000 form could be activated and converted into the fully active 40 000 form, by acid or limited proteolysis. The 70 000 form was activated without change in molecular weight. 3. In addition to its enzymic activity, renin was measured by a direct radioimmunoassay, which revealed that the current acid treatment of plasma did not activate all the renin present. 4. Renin is stored as fully active 40 000 renin, with a specific enzymic reactivity of 0·4 × 10−3 GU ng−1, in the submaxillary gland of mice. 5. Pure 125I-labelled 40 000 submaxillary renin did not bind to plasma proteins. However, by changing the tertiary structure of renin, it was bound to some of the plasma protease inhibitors; α2-macroglobulin, inter-α-trypsin inhibitor and α2-antithrombin. It was also bound to α1- and β1-lipoprotein, albumin and an unidentified plasma protein. No binding was seen to more than 50 other studied plasma proteins.

scholarly journals Dexyribonucleic acid polymerases of BHK-21/C13cells. Relationship to the physiological state of the cells, and to synchronous indution of synthesis of deoxyribonuleic acid

1975 ◽  
Vol 145 (2) ◽  
pp. 233-240 ◽  
Author(s):  
R K Craig ◽  
P A Costello ◽  
H M Keir
Keyword(s):  
Molecular Weight ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Physiological State ◽  
Polymerase Activity ◽  
Quiescent State ◽  
Dna Polymerase I ◽  
Quiescent Cells ◽  
Polymerase I ◽  
Dna Polymerase Ii

BHK-21/C13 cells were grown in culture under conditions that provided exponentially growing cells and quiescent cells, by modifying the concentration of serum in the growth medium. The high-molecular-weight DNA polymerase (DNA polymerase I) from exponentially growing cells accounted for 90% of the total polymerase activity; the low-molecular-weight DNA polymerase (DNA polymerase II) accounted for the remaining 10%. In quiescent cells, DNA polymerase I contributed only 39% of the total polymerase activity and DNA polymerase II 61%. The total amount of DNA polymerase I in exponentially growing cells was 11.3-fold greater than that in quiescent cells, whereas the amount of DNA polymerase II appeared to be relatively independent of the physiological state of the cells. In an extension of these experiments, cells in a quiescent state (Go cells) were stimulated by the ‘serum-step-up’ method of Burk (1970) to grow and to enter a synchronous wave of DNA synthesis (S-phase cells), 87% of the cells synthesizing DNA at 20 h after the ‘serum-step-up’. During the synchrony experiment, the total cytoplasmic and total nuclear DNA polymerase activities each increased about 4-fold in parallel with the increase in the rate of DNA synthesis. Cytoplasmic polymerase activity was always greater than nuclear polymerase activity. The increases observed were maximal at 20 h after ‘serum step-up’. By 26 h, there was a decrease in enzyme activity (8% for cytoplasmic polymerase and 16% for nuclear polymerase, both relative to the maximum at 20 h), but the rate of DNA synthesis had declined by 37% relative to the maximum at 20 h. In Go cells, DNA polymerase II (mol.wt. 46000 +/- 4000) was the predominant species, there being twice as much of it as of the total DNA polymerase I. In these cells there was little DNA polymerase IC and ID; the amounts of IA (mol.wt. 900 times 10(3)-1100 times 10(3)) and IB (mol.wt. 460 times 10(3)-560 times 10(3)) were about equal but small.

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

Interaction of high molecular weight kininogen binding proteins on endothelial cells

2004 ◽  
Vol 91 (01) ◽  
pp. 61-70 ◽  
Author(s):  
Baby Tholanikunnel ◽  
Berhane Ghebrehiwet ◽  
Allen Kaplan ◽  
Kusumam Joseph
Keyword(s):  
Molecular Weight ◽  
Endothelial Cell ◽  
High Molecular Weight ◽  
Gel Filtration ◽  
Surface Proteins ◽  
Factor Xii ◽  
High Molecular Weight Kininogen ◽  
Dot Blot ◽  
Cell Plasma ◽  
Molecular Weight Peak

SummaryCell surface proteins reported to participate in the binding and activation of the plasma kinin-forming cascade includes gC1qR, cytokeratin 1 and u-PAR. Each of these proteins binds high molecular weight kininogen (HK) as well as Factor XII. The studies on the interaction of these proteins, using dot-blot analysis, revealed that cytokeratin 1 binds to both gC1qR and u-PAR while gC1qR and u-PAR do not bind to each other. The binding properties of these proteins were further analyzed by gel filtration. When biotinylated cytokeratin 1 was incubated with either gC1qR or u-PAR and gel filtered, a new, higher molecular weight peak containing biotin was observed indicating complex formation. The protein shift was also similar to the biotin shift. Further, immunoprecipitation of solubilized endothelial cell plasma membrane proteins with anti-gC1qR recovered both gC1qR and cytokeratin 1, but not u-PAR. Immunoprecipitation with anti-u-PAR recovered only u-PAR and cytokeratin 1. By competitive ELISA, gC1qR inhibits u-PAR from binding to cytokeratin 1; u-PAR inhibits gC1qR binding to a lesser extent and requires a 10-fold molar excess. Our data suggest that formation of HK (and Factor XII) binding sites along endothelial cell membranes consists of bimolecular complexes of gC1qR-cytokeratin 1 and u-PAR-cytokeratin 1, with gC1qR binding being favored.

Heterogeneity of High-molecular-weight Human Salivary Mucins

2000 ◽  
Vol 14 (1) ◽  
pp. 69-75 ◽  
Author(s):  
G.D. Offner ◽  
R.F. Troxler
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Biochemical Properties ◽  
Salivary Proteins ◽  
Molecular Weights ◽  
Structural Framework ◽  
Buccal Epithelial Cells ◽  
Membrane Bound ◽  
Membrane Spanning ◽  
Micro Organisms

The existence of high-molecular-weight glycoproteins in saliva and salivary secretions has been recognized for nearly 30 years. These proteins, called mucins, are essential for oral health and perform many diverse functions in the oral cavity. Mucins have been intensively studied, and much has been learned about their biochemical properties and their interactions with oral micro-organisms and other salivary proteins. In the past several years, the major high-molecular-weight mucin in salivary secretions has been identified as MUC5B, one of a family of 11 human mucin gene products expressed in tissue-specific patterns in the gastrointestinal, respiratory, and reproductive tracts. MUC5B is one of four gel-forming mucins which exist as multimeric proteins with molecular weights greater than 20-40 million daltons. The heavily glycosylated mucin multimers form viscous layers which protect underlying epithelial surfaces from microbial, mechanical, and chemical assault. Another class of mucin molecules, the membrane-bound mucins, is structurally and functionally distinct from the gel-forming mucins. These proteins do not form multimers and can exist as both secreted and membrane-bound forms, with the latter anchored to epithelial cell membranes through a short membrane-spanning domain. In the present work, we show that two of the membrane-bound mucins, MUC1 and MUC4, are expressed in all major human salivary glands as well as in buccal epithelial cells. While the functions of these mucins in the oral environment are not understood, it is possible that they form a structural framework on the cell surface which not only is cytoprotective, but also may serve as a scaffold upon which MUC5B, and possibly other salivary proteins, assemble.

scholarly journals α-Crystallin. The isolation and characterization of distinct macromolecular fractions

1971 ◽  
Vol 124 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Abraham Spector ◽  
Lu-Ku Li ◽  
Robert C. Augusteyn ◽  
Arthur Schneider ◽  
Thomas Freund
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Chemical Difference ◽  
Molecular Weights ◽  
Isolation And Characterization ◽  
Different Populations ◽  
Molecular Weight Fractions

α-Crystallin was isolated from calf lens periphery by chromatography on DEAE-cellulose and gel filtration. Three distinct populations of macromolecules have been isolated with molecular weights in the ranges approx. 6×105−9×105, 0.9×106−4×106and greater than 10×106. The concentration of macromolecules at the molecular-weight limits of a population are very low. The members of the different populations do not appear to be in equilibrium with each other. Further, in those molecular-weight fractions investigated, no equilibrium between members of the same population was observed. The population of lowest molecular weight comprises 65–75% of the total material. The amino acid and subunit composition of the different-sized fractions appear very similar, if not identical. The only chemical difference observed between the fractions is the presence of significant amounts of sugar in the higher-molecular-weight fractions. Subunit molecular weights of approx. 19.5×103and 22.5×103were observed for all α-crystallin fractions.

Synthesis of Cyclic Polysulfides and their Properties as Curing Agents

2004 ◽  
Vol 77 (2) ◽  
pp. 380-390
Author(s):  
Wonmun Choi ◽  
Tomoyuki Matsumura
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Mass Spectra ◽  
Elongation At Break ◽  
Molecular Weights ◽  
Aging Properties ◽  
Curing Agents ◽  
Polysulfide Polymer

Abstract The reactions of dichloroalkanes and sodium tetra-sulfide (Na2S4) were carried out in a mixture of water and toluene to produce corresponding cyclic polysulfides and polysulfide polymer. The low molecular weights of cyclic sulfides were obtained by the reaction at 90 °C, while the high molecular weight of polysulfide polymer was obtained by the reaction at 50 °C. GPC chromatograms and Mass spectra revealed that the structures of cyclic polysulfide were 1:1, 2:2, and 3:3 adducts of dichloroalkane and sodium tetra-sulfide. The mechanical properties of vulcanized NR at 148 °C with cyclic sulfides were similar to that with sulfur. However, both tensile strength and elongation at break of vulcanized NR at 170 °C with cyclic sulfides are much higher than that with sulfur. The aging properties of vulcanized NR at 148 °C or 170 °C with cyclic polysulfides indicate better stability.

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