scholarly journals Molecular Weight Distribution and Intrinsic Viscosity of Sonicated and Successively Fractionated Double-Stranded Deoxyribonucleic Acid and Polyribonucleotides

1994 ◽  
Vol 26 (3) ◽  
pp. 291-302 ◽  
Author(s):  
Masato Tanigawa ◽  
Nobuaki Mukaiyama ◽  
Satoshi Shimokubo ◽  
Kengo Wakabayashi ◽  
Yoshimasa Fujita ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Deoxyribonucleic Acid

The kinetics of the polymerization of sarcosine carbonic anhydride

1949 ◽  
Vol 199 (1059) ◽  
pp. 499-517 ◽  
Keyword(s):  
Molecular Weight ◽  
Equilibrium Constant ◽  
Intrinsic Viscosity ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Intermediate Compound ◽  
Preparative Method ◽  
Kinetics Of

The polymerization of carbonic anhydrides, a reaction important but>u as a preparative method for the synthesis of polypeptides and as an example of a less familiar type of polymerization, has been studied in detail using sarcosine carbonic anhydride (I). The propagation reaction has been shown to involve a reversibly formed compound between the carbonic anhydride and the polymer; this compound decomposes by both a unimolecular and a bimolecular route. The equilibrium constant for the formation of the intermediate compound, and both velocity constants for its decomposition have been determined in two solvents, and the energies of activation and frequency factors calculated. The molecular weight distribution has been calculated; it is extremely sharp. The viscosities of the polymers prepared by this reaction have been measured, and the relation between the intrinsic viscosity and the molecular weight established.

scholarly journals A defined molecular-weight distribution of deoxyribonucleic acid after extensive sonication

1978 ◽  
Vol 173 (1) ◽  
pp. 179-183 ◽  
Author(s):  
A W Davis ◽  
D R Phillips
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
High Power ◽  
Weight Distribution ◽  
Deoxyribonucleic Acid ◽  
Tertiary Structure ◽  
Low Molecular Weight ◽  
Concentrated Solutions ◽  
Strand Scission ◽  
Total Dna

Concentrated solutions of low-molecular-weight DNA (Mw=35000) with a known molecular-weight distribution can be prepared in several hours, and require no additional fractionation procedures. This is achieved by sonication of the DNA in 1.0 M-NaCl at high power at 0–2 degrees C. No denaturation of the DNA is detectable, even after 8h of continuous sonication. After 2h, the molecular-weight distribution of the total DNA sample is that of the most probably Schulz distribution, described by-Mn:-Mw:-Mz …=1:2:3 …etc. Such a molecular-weight distribution is expected for a random break-up of indefinitely long macromolecules and indicates that the sonication process is essentially by random double-strand scission. DNA was also sonicated in the presence of ligands capable of modifying the DNA tertiary structure. The results support the idea that inflexibility of the DNA is required for efficient sonic degradation.

Molecular weight – viscosity relationships for a broad molecular weight distribution polymer

1985 ◽  
Vol 63 (1) ◽  
pp. 221-222 ◽  
Author(s):  
H. Kh. Mahabadi ◽  
L. Alexandru
Keyword(s):  
Molecular Weight ◽  
Bisphenol A ◽  
Intrinsic Viscosity ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Simple Method ◽  
Broad Molecular Weight Distribution

A novel and simple method is described for evaluation of molecular weight – viscosity relationships for a polymer where only broad molecular weight distribution samples are available. The method demands measurement of the intrinsic viscosity and GPC chromatograms of several samples. Results of applying the procedure to bisphenol A – Diethyleneglycol (50:50) copolycarbonate are presented.

Extraction and Partial Purification of Protease from Bilimbi (Averrhoa bilimbi L.)

2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe
Keyword(s):  
Molecular Weight ◽  
Protein Content ◽  
Ammonium Sulfate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Protease Activity ◽  
Protein Concentration ◽  
Temperature Stability ◽  
Partial Purification ◽  
Ammonium Sulfate Precipitation

Unripe and ripe bilimbi (Averrhoa bilimbi L.) were ground and the extracted juices were partially purified by ammonium sulfate precipitation at the concentrations of 40 and 60% (w/v). The collected proteases were analysed for pH, temperature stability, storage stability, molecular weight distribution, protein concentration and protein content. Protein content of bilimbi fruit was 0.89 g. Protease activity of both the unripe and ripe fruit were optimum at pH 4 and 40°C when the juice were purified at 40 and 60% ammonium sulfate precipitation. A decreased in protease activity was observed during the seven days of storage at 4°C. Molecular weight distribution indicated that the proteases protein bands fall between IO to 220 kDa. Protein bands were observed at 25, 50 and 160 kDa in both the unripe and ripe bilimbi proteases purified with 40% ammonium sulfate, however, the bands were more intense in those from unripe bilimbi. No protein bands were seen in proteases purified with 60% ammonium sulfate. Protein concentration was higher for proteases extracted with 40% ammonium sulfate at both ripening stages. Thus, purification using 40% ammonium sulfate precipitation could be a successful method to partially purify proteases from bilimbi especially from the unripe stage. 

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