Alcohol. A bigger drug problem?
Explore the source record for details and available documents.
Alcoholism↗
Biomedical subjects
J Rosengren
Publications and source records attributed to J Rosengren.
Chromatographic fractionation of Escherichia coli transfer RNA on a new support, naphthoyl-Sepharose.
The noncharged naphthoyl-Sepharose CL-6B has been prepared. Escherichia coli tRNA binds to this new adsorbent in 0.75 M ammonium sulphate at neutral pH at room temperature. Using a negative salt gradient, the tRNAs are eluted in a defined order. The chromatographic pattern is clearly different from those of other commonly used tRNA separation techniques.
Chromatography↗
Differences in hydrophobic surface characteristics of porcine enteropathogenic Escherichia coli with or without K88 antigen as revealed by hydrophobic interaction chromatography.
Porcine enteropathogenic Escherichia coli strains possessing or lacking K88 antigen were studied by using hydrophobic interaction chromatography on cross-linked agarose gels with alkyl or aryl substituents (amphiphilic gels) to determine whether or not they possessed surface-associated hydrophobic properties. Strains with K88ab or K88ac antigen adsorbed to phenyl and octyl Sepharose gels in the presence of 4 M sodium chloride. This property correlated with phenotypic expression of K88 antigen. Cells grown at 37 degrees C but not those grown at 18 degrees C possessed hydrophobic adsorptive characteristics in addition to the property of mannose-resistant hemagglutination of guinea pig erythrocytes. Adsorption of K88-positive strains to gels with hydrophobic ligands was independent of O group and enterotoxicity. Strains lacking K88 antigen did not adsorb to the hydrophobically substituted derivatives of Sepharose and lacked mannose-resistant hemagglutinating characteristics. Neither the presence of additional polysaccharide K antigens nor nonhemagglutinating pili conferred the property of hydrophobic interaction on the strains. K88-positive bacteria had a lower electrophoretic migration rate than did K88-negative bacteria of the same serotype in free-zone electrophoresis. K88-positive bacteria also adsorbed strongly to hydrophobic ligands in the presence of 1 M ammonium sulfate, whereas K88-negative strains did not. These observations provide evidence for the suspected role of hydrophobic interaction in the adhesive properties of certain enteropathogenic strains of E. coli. Moreover, hydrophobic interaction chromatography provides convenient and rapid alternative means of screening strains for a property potentially associated with adhesiveness.
Adsorption↗
Hydrophobic interaction chromatography on uncharged Sepharose derivatives. Effects of neutral salts on the adsorption of proteins.
In the presence of different neutral salts in high concentrations (ionic strength 1-3 M), pentyl-Sepharose was saturated with human serum albumin, and decyl-Sepharose with ovalbumin and phycoerythrin; the amount of protein bound to the adsorbent was taken as a measure of the hydrophobic interaction. The effects of the different ions on the adsorption of protein could, with one exception, be arranged according to the Hofmeister series. As the adsorption might also be influenced by alterations in the protein conformation, caused by the neutral salts, the proteins were studied by circular dichroism. Circular-dichroism spectra showed that 3 M sodium bromide and 3 M sodium thiocyanate changed the conformation of human serum albumin and ovalbumin, whereas 3 M sodium chloride and 1 M sodium sulphate did not. The conformational changes observed with sodium bromide and thiocyanate were accompanied by decreasing protein-adsorbent interaction, except for ovalbumin in 3 M sodium thiocyanate.
Adsorption↗
Hydrophobic interaction chromatography on non-charged Sepharose derivatives. Binding of a model protein, related to ionic strength, hydrophobicity of the substituent, and degree of substitution (determined by NMR).
A series of agarose gels, substituted with hydrophobic groups, has been synthesized and used for binding studies with the coloured model protein, phycoerythrin. The degrees of substitution for the derivatives can easily be estimated with proton magnetic resonance (NMR). It has been found that the capacity of the derivatives for phycoerythrin increases with increasing hydrophobicity of the substituent, degree of substitution and increasing ionic strength. For column experiments the degree of substitution should lie in the range 40-100 mmol substituent/mol galactose. When it is excessively high, the flow characteristics of the columns are unsatisfactory and difficulties to achieve complete desorption may arise.
Binding Sites↗