The hydrolysis of wool wax and related high molecular weight esters. I. Homogeneous reactions

2007 ◽  
Vol 1 (10) ◽  
pp. 452-453 ◽  
Author(s):  
E. V. Truter
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Hydrolysis Of ◽  
Wool Wax ◽  
Homogeneous Reactions

scholarly journals When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 231
Author(s):  
Mengchen Liao ◽  
Yang Chen ◽  
Michael A. Brook
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Efficient Method ◽  
Heterogeneous Reaction ◽  
Chain Extension ◽  
Molecular Weights ◽  
Second Growth ◽  
The One ◽  
Hydrolysis Of ◽  
Homogeneous Reactions

A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol−1) using the one-shot hydrolysis of MHMH is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol−1). The “living” character of the chain extension processes was demonstrated by adding a small portion of MHMH and B(C6F5)3 (BCF) to a first formed polymer, which led to a ~2-fold, second growth in molecular weight. The heterogeneous reaction reached completion in less than 30 min, much less in some cases, regardless of whether it was performed neat or 50 wt% in dry toluene; homogeneous reactions in toluene were much slower. The process does not involve traditional redistribution, as judged by the low quantities (<3%) of D4 produced. However, it is not possible to avoid Chojnowski metathesis from MHDDMH giving D3, which occurs competitively with chain extension.

scholarly journals Biodegradation of low molecular weight polyacrylamide under aerobic and anaerobic conditions: effect of the molecular weight

2020 ◽  
Vol 81 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Wenzhe Song ◽  
Yu Zhang ◽  
Amir Hossein Hamidian ◽  
Min Yang
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Carbon Chain ◽  
Anaerobic Treatment ◽  
Low Molecular Weight ◽  
Amino Groups ◽  
Molecular Weights ◽  
Weight One ◽  
Hydrolysis Of ◽  
Aerobic And Anaerobic

Abstract The biodegradation of polyacrylamide (PAM) includes the hydrolysis of amino groups and cleavage of the carbon chain; however, the effect of molecular weight on the biodegradation needs further investigations. In this study, biodegradation of low molecular weight PAM (1.6 × 106 Da) was evaluated in two aerobic (25 °C and 40 °C) and two anaerobic (35 °C and 55 °C) reactors over 100 days. The removal of the low molecular weight PAM (52.0–52.6%) through the hydrolysis of amino groups by anaerobic treatment (35 °C and 55 °C) was much higher than that of the high molecular weight (2.2 × 107 Da, 11.2–17.0%) observed under the same conditions. The molecular weight was reduced from 1.6 × 106 to 6.45–7.42 × 105 Da for the low molecular weight PAM, while the high molecular weight PAM declined from 2.2 × 107 to 3.76–5.87 × 106 Da. The results showed that the amino hydrolysis of low molecular weight PAM is easier than that of the high molecular weight one, while the cleavage of its carbon chain is still difficult. The molecular weights of PAM in the effluents from the two aerobic reactors (25 °C and 40 °C) were further reduced to 4.31 × 105 and 5.68 × 105 Da by the biofilm treatment, respectively. The results would be useful for the management of wastewater containing PAM.

scholarly journals Ca2+-Induced Cleavage of Human Platelet Polypeptides Mediated by the Calcium Ionophore A-23187

1977 ◽  
Author(s):  
Milica Jakábová ◽  
David R. Phillips
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Proteolytic Activity ◽  
Platelet Activation ◽  
Human Platelet ◽  
Calcium Ionophore ◽  
Lactic Dehydrogenase ◽  
Actin Binding ◽  
A 23187 ◽  
Hydrolysis Of

The effect of calcium on human platelet polypeptides was investigated. When lysed platelets were incubated with mM Ca++, two major intracellular polypeptides (Mr = 255,000 and 230,000) were found to rapidly disappear. A similar phenomenon was also observed when intact platelets were treated with the calcium ionophore A-23187 in the presence of mM Ca++. Determinations of lactic dehydrogenase activity in supernatant fractions demonstrated that these losses occurred before platelet lysis. Investigations into the identity of the high molecular weight polypeptides revealed that one (Mr = 255,000) had similar properties to actin binding protein. The loss of the high molecular weight polypeptides was accompanied by formation of lower molecular weight polypeptides (Mr = 135,000, 93,000 and 48,000), indicating that Ca++ activates a polypeptide cleavage mechanism. The Ca++-activated polypeptide cleavages were rapid, with significant changes being observed within the first 0.5 min of incubation. An obvious explanation for these effects is. that there is Ca++-activated proteolytic activity within platelets. The Ca++-activated proteolytic activity was determined by the hydrolysis of the artificial substrate azocasein. We found that more than 90% of the proteolytic activity in lysed platelets was due to Ca++-activated proteases. These studies show that Ca++-activated proteases may play an important role in platelet activation.

"Colloidal" Phosphorus Errors in Gel Chromatography

1983 ◽  
Vol 40 (10) ◽  
pp. 1614-1621 ◽  
Author(s):  
B. Kent Burnison
Keyword(s):  
Molecular Weight ◽  
Acid Hydrolysis ◽  
High Molecular Weight ◽  
Gel Chromatography ◽  
Chemical Analyses ◽  
Molybdophosphoric Acid ◽  
Molybdenum Blue ◽  
Soluble Reactive Phosphate ◽  
Colloidal Phosphorus ◽  
Hydrolysis Of

Gel chromatography has been used for the separation of 32PO4 and a high molecular weight "colloidal" 32P-labeled fraction from 32PO4-labeled lakewater. When the labeled filtrate is treated with reagents required for the molybdenum blue method for orthophosphate analysis, only a small fraction of the "colloidal" peak is hydrolyzed to orthophosphate. As the reduced molybdophosphoric acid is strongly adsorbed to the dextran gel, quantitative elution of 32PO4 can be achieved with 0.05 mol∙L−1 NaOH and 0.3% NaCl. In hardwater lakes, care must be taken to eliminate the possibility of orthophosphate precipitation at higher pH. In these lakes, it is unlikely that the discrepancy between 32PO4 bioassays and chemical analyses can be solely attributed to acid hydrolysis of "colloidal" phosphorus. Microparticulate apatite also has the potential to release soluble reactive phosphate when the acidic molybdenum blue method is used.

END GROUP AND SEDIMENTATION DATA ON FRAGMENTED HIGH MOLECULAR WEIGHT RIBONUCLEATES

1963 ◽  
Vol 41 (1) ◽  
pp. 1927-1941 ◽  
Author(s):  
B. G. Lane ◽  
J. Diemer ◽  
C. A. Blashko
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Snake Venom ◽  
Group Analysis ◽  
Sedimentation Coefficient ◽  
Snake Venom Phosphodiesterase ◽  
Ehrlich Ascites ◽  
Spontaneous Hydrolysis ◽  
Hydrolysis Of ◽  
End Group

A method for end group analysis of ribonucleate preparations using purified snake venom phosphodiesterase is described. Unusual difficulties encountered with the method are discussed. The technique is useful for detection of end groups resulting from enzymic and chemical fragmentation of high molecular weight ribonucleates. Preliminary studies indicate that the method has limited usefulness because of a spontaneous hydrolysis of ribonucleates which occurs under the conditions which are optimal for hydrolysis with snake venom phosphodiesterase (pH 9, in the presence of magnesium). Physicochemical studies have shown that the pronounced dependence of sedimentation coefficient on ionic strength which has been reported by other investigators is also observed with fragmented high molecular weight ribonucleates and with 16S + 24S ribonucleates of Ehrlich ascites cells. The changes of sedimentation rate are associated with configurational and aggregation effects.

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