scholarly journals Some Effects of Pressure Treatment on Actomyosin Systems

1976 ◽  
Vol 29 (3) ◽  
pp. 197 ◽  
Author(s):  
JM O'Shea ◽  
DJ Horgan ◽  
J JMacfarlane
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Atpase Activity ◽  
Pressure Treatment ◽  
Large Measure ◽  
Actin Depolymerization ◽  
Scattering Measurements

Natural actomyosin, actin and myosin, have been pressurized at up to 150 MN/m2 for 1 h at O�C and examined 3-5 h later. Pressurization of myosin resulted in the formation of aggregates with a molecular weight approximately that expected for a dimer, whereas with F-actin depolymerization occurred. With actomyosin, a gel to sol transition was promoted. Viscosity and light-scattering measurements indicated that pressurization results in a large measure of disaggregation of actomyosin in solution. Pressurization of actomyosin resulted in a greater decrease in the calcium-sensitive, than in the calcium-independent, Mg2+ ATPase activity. The Ca2+ and K+-EDTA ATPase activities of myosin were inhibited to about the same extent.

A STUDY OF A WATER-SOLUBLE COMPLEX OF PRODIGIOSIN PRODUCED BY A STRAIN OF SERRATIA MARCESCENS

1962 ◽  
Vol 40 (1) ◽  
pp. 1019-1024 ◽  
Author(s):  
Seiichi Yoshida
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Serratia Marcescens ◽  
Average Molecular Weight ◽  
Electrophoretic Analysis ◽  
Water Soluble ◽  
Soluble Complex ◽  
Ph Values ◽  
Scattering Measurements ◽  
Water Soluble Complex

A water-soluble pigment excreted from Serratia marcescens has been purified by precipitation with ammonium sulphate, dialysis, and ultracentrifugation at different pH values. The purified pigment showed a single band in the ultracentrifuge and by electrophoretic analysis at several pH values. An average molecular weight of 5 × 106 was calculated from light-scattering measurements. This pigment is composed of carbohydrate and protein combined with prodigiosin, and several properties of the complex are described.

Light Scattering and Flow Dichroism Studies on DNA After the Photoreaction with Psoralen

1972 ◽  
Vol 27 (2) ◽  
pp. 196-200 ◽  
Author(s):  
S. Marciani ◽  
M. Terbojevic ◽  
F. Dall’Acqua
Keyword(s):  
Heat Treatment ◽  
Molecular Weight ◽  
Light Scattering ◽  
Double Helix ◽  
Heat Denaturation ◽  
Scattering Measurements ◽  
Helix Structure ◽  
Double Helix Structure

Light scattering measurements performed on DNA after irradiation in the presence of psoralen clearly show that inter strand cross linkings are present in the macromolecule. In fact after heat denaturation and successive cooling irradiated macromolecule shows a molecular weight practically unchanged while a DNA sample after the same treatment shows a molecular weight half of the intact native DNA. Also the general conformation of irradiated DNA undergoes practically to no modifications after the same heat treatment while native DNA shows itself to have been strongly modified. Moreover, on the basis of flow dichroism determinations, DNA cross-linked by psoralen after heat denaturation showed to be able to restore its ordered double helix structure, during the successive cooling.

A STUDY OF A WATER-SOLUBLE COMPLEX OF PRODIGIOSIN PRODUCED BY A STRAIN OF SERRATIA MARCESCENS

1962 ◽  
Vol 40 (8) ◽  
pp. 1019-1024 ◽  
Author(s):  
Seiichi Yoshida
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Serratia Marcescens ◽  
Average Molecular Weight ◽  
Electrophoretic Analysis ◽  
Water Soluble ◽  
Soluble Complex ◽  
Ph Values ◽  
Scattering Measurements ◽  
Water Soluble Complex

A water-soluble pigment excreted from Serratia marcescens has been purified by precipitation with ammonium sulphate, dialysis, and ultracentrifugation at different pH values. The purified pigment showed a single band in the ultracentrifuge and by electrophoretic analysis at several pH values. An average molecular weight of 5 × 106 was calculated from light-scattering measurements. This pigment is composed of carbohydrate and protein combined with prodigiosin, and several properties of the complex are described.

DISSOCIATION AND SUBUNIT SIZE OF β-LIPOVITELLIN

1965 ◽  
Vol 43 (6) ◽  
pp. 661-670 ◽  
Author(s):  
W. H. Cook ◽  
R. A. Wallace
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Dissociation Constants ◽  
Dry Weight ◽  
Ph Values ◽  
Scattering Measurements ◽  
Solvent Displacement ◽  
Weight Method ◽  
Kinetics Of ◽  
Good Agreement

Dissociation of β-lipovitellin was detectable at pH 5.8 and increased linearly with pH. Light-scattering measurements at different pH values were consistent with a molecular weight of 2.27 × 105 for the subunit and twice this value for the associated form, confirming that it is a monomer–dimer system. This value for the molecular weight of the dimer is somewhat higher than previously reported (4.0 × 105) partly because a solvent displacement correction was used in estimating concentration by a dry weight method. Dissociation constants evaluated from light-scattering measurements and by ultracentrifugal separation were 22 × 10−6 and 29 × 10−6 respectively, in good agreement with provisional values already reported. Preliminary studies on the kinetics of this reaction indicate that, when the pH is altered, dissociation reaches the new equilibrium in about 0.5 minute but that reassociation requires about 50 minutes.

scholarly journals MOLECULAR SIZE AND CONFIGURATION OF CELLULOSE TRINITRATE IN SOLUTION

1958 ◽  
Vol 36 (6) ◽  
pp. 952-969 ◽  
Author(s):  
M. M. Huque ◽  
D. A. I. Goring ◽  
S. G. Mason
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Ethyl Acetate ◽  
Average Molecular Weight ◽  
Molecular Size ◽  
Random Coil ◽  
Radius Of Gyration ◽  
Molecular Weight Range ◽  
Scattering Measurements ◽  
The Relationship

Viscosity and light-scattering measurements were made on several fractions and two unfractionated samples of cellulose trinitrate. The samples were prepared from bleached ramie, unbleached ramie, and cotton linters. The solvents were acetone and ethyl acetate. Viscosity was measured in a multishear viscometer designed for the purpose. Light-scattering measurements were made in a Brice-Phoenix Light-scattering Photometer modified to accommodate a cell which could be ultracentrifuged.The range of molecular weight investigated was from 6.5 × 105 to 25.0 × 105 The relationship between the z-average mean-square radius of gyration, [Formula: see text] and the z-average molecular weight was approximately linear in both solvents. The ratio of [Formula: see text] (where [Formula: see text] is the value of [Formula: see text] in the unperturbed state) was found constant in acetone but to increase with [Formula: see text] in ethyl acetate. This indicated that, whereas in acetone random coil configuration was attained, a configurational transition occurred in ethyl acetate in the molecular weight range investigated.The value of the exponent a in the relationship between intrinsic viscosity and molecular weight was found to be lower than unity but approximately equal in both solvents.The significance of the experimental data is discussed.

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