Liquid Rubbers—General Rubber Products Technology

1971 ◽  
Vol 44 (3) ◽  
pp. 750-757 ◽  
Author(s):  
J. R. Pyne
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Raw Material ◽  
Development Work ◽  
Low Molecular Weight ◽  
Scale Production ◽  
Theoretical Possibility ◽  
High Molecular Weight Form ◽  
End Groups ◽  
Molecular Weight Form

Abstract Mixing and processing methods used in the rubber industry have been designed to use the only form of raw rubber hitherto available—that of a high molecular weight solid. But rubber in high molecular weight form is essential only in the finished product; in principle, similar final properties could be obtained from a low molecular weight raw material provided this could be chain extended before or during the final shaping and vulcanizing operation. This approach has been employed for some time in the rather specialized field of castable polyurethane rubber manufacture. Its exploitation for more general rubber manufacture has become more than just a theoretical possibility with the recent availability of “liquid rubbers” whose molecules have reactive end groups. Those available at present may well prove not fully acceptable, either economically or technically, but it is most unlikely that they represent the best that can be achieved. Material developments will be encouraged if means have been worked out for exploiting liquid rubbers' potential advantages (such as the ability to be processed on lighter and less powerful equipment), and the shortcomings of existing examples have been identified. These considerations led RAPRA to start a processing and compounding study—a decision which seems further justified by the very recent American announcements of development work on a tire manufacturing process using liquid rubber, and of full commerical scale production of several hydroxyl terminated liquid butadiene polymers. This report summarizes the study to date.

scholarly journals Conversion of low molecular weight renin into the high molecular weight form by Cu2+ in the rat kidney.

1984 ◽  
Vol 7 (11) ◽  
pp. 820-829
Author(s):  
SHIRO MORIMOTO ◽  
KATSUJHIKO ITO ◽  
TAKAHIRO IWAMOTO ◽  
YUKA KOSEDA ◽  
MASANORI TAKAOKA
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Rat Kidney ◽  
Low Molecular Weight ◽  
High Molecular Weight Form ◽  
Molecular Weight Form

scholarly journals Thermal Instability of the Trimeric Structure of the N-terminal Propeptide of Human Procollagen Type I in Relation to Assay Technology

1999 ◽  
Vol 45 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Jette Brandt ◽  
Thomas N Krogh ◽  
Charlotte H Jensen ◽  
Jette K Frederiksen ◽  
Børge Teisner
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Type I ◽  
Thermal Transition ◽  
Procollagen Type ◽  
High Molecular Weight Form ◽  
Procollagen Type I ◽  
Trimeric Structure ◽  
Molecular Weight Form

Abstract The N-terminal propeptide of procollagen type I (PINP) appeared in two peaks after size chromatography. The high-molecular weight form was transformed to the low-molecular weight form during incubation at 37 °C, whereas the low-molecular weight form remained unchanged. The PINP concentrations in amniotic fluid and sera remained unchanged during 37 °C incubation when measured using an ELISA; however, concentrations decreased by 89–93% when measured using an RIA. The ELISA:RIA ratio varied from 1.1 to 2.9 in these fluids because of different size distributions and the inability of the RIA to measure the low-molecular weight form. Thermal transition of the high-molecular weight form caused a change in its elution volume but did not change its migration in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Mass spectrometry revealed identical results for both forms. We reached the following conclusions: (a) the trimeric structure of PINP is unstable at 37 °C; (b) the two molecular forms represent intact α1 chains in trimeric and monomeric forms; (c) thermal transition is an ongoing in vivo process; and (d) this is important in the choice of assay technology.

Interconversion between High- and Low-Molecular-Weight Forms of Renin in Dog Kidney

1980 ◽  
Vol 59 (s6) ◽  
pp. 25s-27s ◽  
Author(s):  
K. Yamamoto ◽  
F. Ikemoto ◽  
M. Kawamura ◽  
K. Takaori
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Apparent Molecular Weight ◽  
Kidney Cortex ◽  
Low Molecular Weight ◽  
Cytosol Fraction ◽  
High Molecular Weight Form ◽  
Binding Substance ◽  
Dog Kidney ◽  
Molecular Weight Form

1. The low-molecular-weight (40 000) form of renin was converted into the high-molecular-weight (60 000) form of renin with sulphydryl oxidation, and the high-molecular-weight form of renin was re-converted into the low-molecular-weight form with a reduction of disulphide bonds in the renal cortical homogenate of the dog. Therefore, the low- and high-molecular-weight forms of renin were interconvertible. 2. The formation of high-molecular-weight form of renin required a renin binding substance which was found to be included in the cytosol fraction of kidney cortex of the dog. 3. The renin binding substance of the dog was unstable to heat and low pH, but vitally resistant to Triton X-100 and chloroform. It did not bind to concanavalin A Sepharose 4B. 4. The renin binding substance was eluted in the molecular-weight region between 156 000 and 60 000 on Sephadex G-200, and such apparent molecular weight was not altered by urea at 4 mol/l; thus molecular weight greater than the theoretically expected value of 20 000 was indicated.

Spreading of microinjected horseradish peroxidase to nondescendant cells in embryos of Patella (Mollusca, Gastropoda)

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 713-722
Author(s):  
W.M. Kuhtreiber ◽  
F. Serras ◽  
J.A.M. van den Biggelaar
Keyword(s):  
Molecular Weight ◽  
Stem Cell ◽  
Horseradish Peroxidase ◽  
High Molecular Weight ◽  
Fluorescein Isothiocyanate ◽  
Contact Phase ◽  
High Molecular Weight Form ◽  
Contact Stage ◽  
Fluorescein Isothiocyanate Dextran ◽  
Molecular Weight Form

We have injected horseradish peroxidase (HRP) and fluorescein-isothiocyanate dextran (FD) into cells and into the blastocoelic cavity of Patella vulgata embryos, before and during the interval between 5th and 6th cleavage, in which the mesodermal stem cell is determined by means of interactions between the central 3D macromere and the contacting animal micromeres. Intracellular injections of HRP at different stages showed that, whereas before this contact phase no spreading of label was observed, a clear intercellular transfer of HRP was found after the contact was established. Control experiments showed that it was HRP in its intact, high molecular weight form that was transferred in the living embryo. Injections of HRP into the blastocoelic cavity gave essentially the same results. In these cases, the HRP was taken up by the cells from contact stage onwards. When FD was injected into the blastocoelic cavity, no uptake was observed, not even after prolonged presence of FD in it. However, when HRP and FD were mixed, both were taken up, starting at contact stage. Differences in labelling pattern of HRP, as compared with FD, and a shift of the FD fluorescence after uptake, suggest that receptor-mediated endocytosis is involved. The possible morphogenetic significance of the transfer mechanism is discussed.

scholarly journals The interrelations between high- and low-molecular-weight forms of normal and mutant (Krabbe-disease) galactocerebrosidase

1980 ◽  
Vol 189 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Yoav Ben-Yoseph ◽  
Melinda Hungerford ◽  
Henry L. Nadler
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Active Form ◽  
Sodium Dodecyl ◽  
Krabbe Disease ◽  
Low Molecular Weight ◽  
Molecular Weight Form

Galactocerebrosidase (β-d-galactosyl-N-acylsphingosine galactohydrolase; EC 3.2.1.46) activity of brain and liver preparations from normal individuals and patients with Krabbe disease (globoid-cell leukodystrophy) have been separated by gel filtration into four different molecular-weight forms. The apparent mol.wts. were 760000±34000 and 121000±10000 for the high- and low-molecular-weight forms (peaks I and IV respectively) and 499000±22000 (mean±s.d.) and 256000±12000 for the intermediate forms (peaks II and III respectively). On examination by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis, the high- and low-molecular-weight forms revealed a single protein band with a similar mobility corresponding to a mol.wt. of about 125000. Antigenic identity was demonstrated between the various molecular-weight forms of the normal and the mutant galactocerebrosidases by using antisera against either the high- or the low-molecular-weight enzymes. The high-molecular-weight form of galactocerebrosidase was found to possess higher specific activity toward natural substrates when compared with the low-molecular-weight form. It is suggested that the high-molecular-weight enzyme is the active form in vivo and an aggregation process that proceeds from a monomer (mol.wt. approx. 125000) to a dimer (mol.wt. approx. 250000) and from the dimer to either a tetramer (mol.wt. approx. 500000) or a hexamer (mol.wt. approx. 750000) takes place in normal as well as in Krabbe-disease tissues.

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