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At least 523 records · Page 29Linked to original sources
PubMed1997

The structure of Silurus asotus (catfish) roe lectin (SAL): identification of a noncovalent trimer by mass spectrometry and analytical ultracentrifugation.

We identified a noncovalent trimer of Sirurus asotus roe lectin (SAL) at Mr 95,362 along with its monomer at M(r) 31,750 by electrospray ionization mass spectrometry when SAL was dissolved in 0.5% acetic acid, sprayed into the ion source with methanol as a sheath liquid, and desolvated at 75 degrees C in a heated capillary column. The molecular weight of SAL, determined by the sedimentation equilibrium method, was 95,200 and the sedimentation coefficient (S20,w) of SAL in water was 5.58. SAL existed as a noncovalent trimer in solution and showed the ability to agglutinate rabbit erythrocytes. SAL showed three peaks (sal 1, sal 2, and sal 3) by C8 reverse-phase HPLC, and these appeared to be a monomer, a dimer, and a trimer, respectively, by matrix-assisted laser desorption ionization-time of flight mass spectrometry, sal 1 and sal 2 were shown to have a structure interchangeable with that of sal 3 in water.

Amino Acids↗
PubMed2001

A potential role for the analytical ultracentrifuge in the experimental measurement of protein valence.

A method is described whereby sedimentation velocity is combined with equilibrium dialysis to determine the net charge (valence) of a protein by using chromate as an indicator ion for assessing the extent of the Donnan redistribution of small ions. The procedure has been used in experiments on bovine serum albumin under slightly alkaline conditions (pH 8.0, I 0.05) to illustrate its application to a system in which the indicator ion and protein both bear net negative charge and on lysozyme under slightly acidic conditions (pH 5.0, I 0.10) to illustrate the situation where chromate is a counterion.

Animals↗
PubMed1982

Demonstration of rubella-specific IgM by serum ultracentrifugation on sucrose gradients: comparison of a vertical and a swinging bucket rotor.

The performances of a vertical and a swinging bucket rotor in the diagnosis of rubella-specific IgM were compared using two sets of predominantly low titre rubella IgM positive sera. Applying a number of subtle criteria, the vertical rotor was shown to separate IgM and IgG less well than the swinging bucket rotor. If the vertical rotor was loaded with pretreated sera with IgG content decreased severalfold, its performance was similar to that of the swinging bucket rotor with native serum. The findings are discussed from the aspect of the main indication of rubella IgM testing, and it was concluded that for the majority of cases the vertical rotor would not present an alternative to the swinging bucket rotor.

Antibodies, Viral↗
PubMed1976

Determination of background serum density for lipoprotein ultracentrifugation.

It is necessary to know the density of serum exclusive of its macromolecules (background density) prior to density adjustment with solid potassium bromide for ultra-centrifugal separation of lipoprotein fractions. To evaluate this, we compared the densities of the corresponding ultrafiltrates or dialysates of both human and equine sera produced by ultrafiltration and equilibrium dialysis method for macromolecule removal. Excellent correlation is found between background densities determined following ultrafiltration or equilibrium dialysis. These data validate the use of ultrafiltration as a simple, direct method for determination of background serum densities but reveal equilibrium dialysis to be more time consuming and less precise. Using ultrafiltration, we find the background density for equine serum to be 1.004 g/ml, and initial investigation suggests this value may be altered by freezing, prolonged refrigeration (3 months), or heating to inactivate lecithin: cholesterol acyltransferase.

Animals↗
PubMed2001

Self-association studies on the EphB2 receptor SAM domain using analytical ultracentrifugation.

The self-association behavior of the Eph-kinases SAM domain has been studied in phosphate buffer, pH 7.4, containing 0.14 M NaCl using concentration-dependent sedimentation equilibrium experiments. Only weak interactions typical for a monomer-dimer equilibrium up to at least 12 mg/mL were observed. Such concentrated solutions require a consideration of the non-ideality expressed by virial coefficients. A special centrifuge equation was used for the global analysis to estimate equilibrium constants based on the thermodynamic activities of the reactants. When neglecting this, the parameters deviate by about 20%. Association constants for dimerization of the EphB2-SAM domain vary between 163 M(-1) at 10 degrees C and 395 M(-1) at 32 degrees C, indicating hydrophobic forces are involved in the dimerization process. In solutions of about 12 mg/mL, less than 50% dimers are in solution and higher oligomers can be excluded.

Amino Acid Motifs↗